Photoelectric conversion element, image pickup element, laminated image pickup element, and solid-state image pickup device

ABSTRACT

An image pickup element is constituted by laminating at least a first electrode, an organic photoelectric conversion layer, and a second electrode in order, and the organic photoelectric conversion layer includes a first organic semiconductor material having the following structural formula (1).

TECHNICAL FIELD

The present disclosure relates to a photoelectric conversion element, animage pickup element, a laminated image pickup element, and asolid-state image pickup device.

BACKGROUND ART

An image pickup element using an organic material (organic photodiode)can photoelectrically convert only a specific color (wavelength band).Then, because of having such a feature, when the organic photodiode isused as an image pickup element in a solid-state image pickup device, asub-pixel is constituted by a combination of an on-chip color filter(OCCF) and an image pickup element. It is possible to obtain a structure(laminated image pickup element) in which the sub-pixels are laminatedon one another. Such a structure is impossible in a past solid-stateimage pickup device in which the sub-pixels are two-dimensionallyarranged. Therefore, since incident light can be received at a highefficiency, the promotion of high sensitivity of the solid-state imagepickup device is expected. In addition, since mosaic processing is notrequired, there is an advantage that a false color does not occur.

The organic photodiode used in the solid-state image pickup device andthe image pickup element has the same or similar structure as or to thatof various organic thin film solar cells. Heretofore, a structureutilizing p-n junction or p-i-n junction (for example, JP 2006-033942A),a structure utilizing a bulk-hetero structure (for example, JP2007-123707A), and a structure utilizing a buffer layer (for example, JP2007-311647A and JP 2007-088033A) has been well known as the structureof the organic photodiode, and have exclusively aimed at enhancing thephotoelectric conversion efficiency.

CITATION LIST Patent Literature

-   [PTL 1]

JP 2006-033942A

-   [PTL 2]

JP 2007-123707A

-   [PTL 3]

JP 2007-311647A

-   [PTL 4]

JP 2007-088033A

Non Patent Literature

-   [NPL 1]

Chem. Rev. 107, 953 (2007)

SUMMARY Technical Problem

Now, a diffusion distance of excitons of the almost organic materialsare 20 nm or less, and a conversion efficiency thereof is generally lowas compared with that of the inorganic solar cell represented bysilicon. In addition, in general, as compared with the case of thesilicon system semiconductor material, the organic material is high inresistance, and low in mobility and carrier density (for example, referto Chem. Rev. 107, 953 (2007)). Therefore, the organic photodiode hasnot yet depicted the characteristics which bears comparison with thoseof the photodiode using the past inorganic material represented bysilicon. However, the organic material having a high absorptioncoefficient as compared with the photodiode using the silicon systemsemiconductor material exists, and thus the promotion of the highsensitivity is expected in the photodiode using such an organicmaterial. Since the absorption coefficient is a physical quantity whichis uniquely defined in silicon, the enhancement of the characteristicsby the absorption coefficient cannot be attained in the photodiode usingthe silicon system semiconductor material.

Therefore, an object of the present disclosure is to provide an imagepickup element (including a laminated image pickup element) and aphotoelectric conversion element each using an organic material havingexcellent optical absorption properties, and a solid-state image pickupdevice provided with such an image pickup element.

Solution to Problem

An image pickup element according to a first aspect of the presentdisclosure for attaining the object described above or a photoelectricconversion element according to the first aspect of the presentdisclosure is constituted by laminating at least a first electrode, anorganic photoelectric conversion layer, and a second electrode in order,and the organic photoelectric conversion layer includes a first organicsemiconductor material having the following structural formula (1).

Here, R₁ and R₂ are each groups independently selected from hydrogen, anaromatic hydrocarbon group, a heterocyclic group, a halogenated aromaticgroup, or a fused heterocyclic group, and have an optional substituent,

the aromatic hydrocarbon group is an aromatic hydrocarbon group selectedfrom the group consisting of a phenyl group, a naphthyl group, ananthryl group, a phenanthryl group, a pyrenyl group, and a benzopyrenylgroup,

the heterocyclic group is a heterocyclic group selected from the groupconsisting of a pyridyl group, a pyradyl group, a pyrimidyl group, aquinolyl group, an isoquinolyl group, a pyrrolyl group, an indolenylgroup, an imidazolyl group, a thienyl group, a furyl group, a pyranylgroup, and a pyridonyl group,

the halogenated aromatic group is a halogenated aromatic group selectedfrom the group consisting of a phenyl group, a naphthyl group, ananthryl group, a phenanthryl group, a pyrenyl group, and a benzopyrenylgroup, and

the fused heterocyclic group is a fused heterocyclic group selected fromthe group consisting of a benzoquinolyl group, an anthraquinolyl group,and a benzothienyl group.

An image pickup element according to a second aspect of the presentdisclosure for attaining the object described above, or a photoelectricconversion element according to the second aspect of the presentdisclosure is constituted by laminating at least a first electrode, anorganic photoelectric conversion layer, and a second electrode in order,and the organic photoelectric conversion layer includes a first organicsemiconductor material having the following structural formula (2):

A laminated image pickup element of the present disclosure for attainingthe object described above is constituted by laminating at least twoimage pickup elements according to the first aspect and the secondaspect of the present disclosure.

A solid-state image pickup device according to a first aspect of thepresent disclosure for attaining the object described above is providedwith a plurality of image pickup elements according to the first aspectand the second aspect of the present disclosure. In addition, asolid-state image pickup device according to a second aspect of thepresent disclosure for attaining the object described above is providedwith a plurality of laminated image pickup elements of the presentdisclosure.

Advantageous Effect of Invention

In the image pickup element according to the first aspect and the secondaspect of the present disclosure, the photoelectric conversion elementaccording to the first aspect and the second aspect of the presentdisclosure, the image pickup element constituting the laminated imagepickup element of the present disclosure, and an image pickup elementconstituting the solid-state image pickup device according to the firstaspect and the second aspect of the present disclosure (hereinafter,those are collectively referred to as “the image pickup device, etc. ofthe present disclosure” in some cases), using the material expressed byeither the structural formula (1) or the structural formula (2) andhaving the high hole mobility in the organic photoelectric conversionlayer enables the photoelectric conversion efficiency and the carriermobility to be greatly enhanced. It should be noted that the effectdescribed in this description is merely the exemplification(s), and isby no means limited. In addition, the additional effect(s) may beoffered.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of an image pickup element ora photoelectric conversion element of Example 1.

FIG. 2 is a conceptual diagram of a solid-state image pickup device ofExample 1.

FIG. 3 is a graphical representation depicting a relationship betweenhole mobility and a conversion efficiency of a p-type semiconductormaterial constituting an organic photoelectric conversion layer in theimage pickup element of Example 1 and Comparative Example 1.

FIG. 4 is a graphical representation depicting spectral characteristicsof an organic photoelectric conversion layer in an image pickup elementof Example 2A.

FIG. 5A is a conceptual view of a p/n junction surface as a boundarybetween a p-type semiconductor material and an n-type semiconductormaterial, FIG. 5B is a schematic view depicting a p/n junction surfacestructure of 6×6×6 nm³ manufactured by a molecular dynamics method, andFIG. 5C is a schematic view in which a dimer of2,7-Diphenyl-[1]benzothieno[3,2-b][1]benzothiophene (DPh-BTBT) andF6SubPc-OC6F5 is selected from which an exciton charge separation rateis described to be obtained, and a molecule having the center of gravityin a radius of 2.5 nm from the center of gravity of DPh-BTBT is takenout, the molecule depicted in the form of ball-and-stick display beingthe dimer from which the exciton charge separation rate is desired to beobtained, and the molecule depicted in the form of line display being aperipheral molecule.

FIG. 6 is a graphical representation depicting a relationship between anoverlap area of energy distributions of LUMO and carrier mobility whichis obtained based on various second organic semiconductor materials andthird organic semiconductor materials.

FIG. 7 is a graphical representation depicting a relationship between avalue of the energy distribution σ of LUMO of the third organicsemiconductor material, and carrier mobility.

FIG. 8 is a view depicting a state of overlap of energy distributions ofLUMO which is obtained based on the second organic semiconductormaterial and the third organic semiconductor material in Example 2B andExample 2C.

FIG. 9 is a view depicting a state of overlap of energy distributions ofLUMO which is obtained based on the second organic semiconductormaterial and the third organic semiconductor material in Example 2D andExample 2E.

FIG. 10 is a view depicting a state of overlap of energy distributionsof LUMO which is obtained based on the second organic semiconductormaterial and the third organic semiconductor material in Example 2F andExample 2G.

FIG. 11 is a view depicting a state of overlap of energy distributionsof LUMO which is obtained based on the second organic semiconductormaterial and the third organic semiconductor material in ComparativeExample 2B and Comparative Example 2C.

FIG. 12 is a view depicting a state of overlap of energy distributionsof LUMO which is obtained based on the second organic semiconductormaterial and the third organic semiconductor material in ComparativeExample 2D and Comparative Example 2E.

FIG. 13 is a view depicting a state of overlap of energy distributionsof LUMO which is obtained based on the second organic semiconductormaterial and the third organic semiconductor material in ComparativeExample 2F and Comparative Example 2G.

FIG. 14 is a view depicting a state of overlap of energy distributionsof LUMO which is obtained based on the second organic semiconductormaterial and the third organic semiconductor material in ComparativeExample 2H and Comparative Example 21.

FIG. 15A and FIG. 15B are conceptual views of laminated image pickupelement of Example 3.

DESCRIPTION OF EMBODIMENTS

Hereinafter, although the present disclosure is described based onExamples with reference to the drawings, the present disclosure is by nomeans limited to Examples, and various numerical values and materials inExamples are exemplifications. It should be noted that a descriptionwill be given in the following order.

1. Description about whole of image pickup elements according to firstaspect and second aspect of present disclosure, photoelectric conversionelements according to first aspect and second aspect of presentdisclosure, laminated image pickup element of present disclosure, andsolid-state image pickup devices according to first aspect and secondaspect of present disclosure.2. Example 1 (image pickup elements and photoelectric conversionelements of present disclosure according to first aspect and secondaspect of present disclosure, and solid-state image pickup deviceaccording to first aspect of present disclosure)3. Example 2 (modified changes of Example 1)4. Example 3 (laminated image pickup element of present disclosure andsolid-state image pickup device according to second aspect of presentdisclosure)

5. Others

<Description about Whole of Image Pickup Elements According to FirstAspect and Second Aspect of Present Disclosure, Photoelectric ConversionElements According to First Aspect and Second Aspect of PresentDisclosure, Laminated Image Pickup Element of Present Disclosure, andSolid-State Image Pickup Devices According to First Aspect and SecondAspect of Present Disclosure>

In an image pickup element, etc. of the present disclosure,

an organic photoelectric conversion layer further includes a secondorganic semiconductor material,

the second organic semiconductor material can be made to have a formconstituted by fullerene (such as higher fullerene such as C60, C70 orC74, or endohedral fullerene) or a fullerene derivative (such as amodified fullerene compound such as a fullerene fluoride or a fullerenemultimers). In the following, for convenience, the materials having astructural formula (1) and a structural formula (2) constituting theorganic photoelectric conversion layer are collectively referred as “abenzothienobenzothiophene system organic material in the presentdisclosure.” Here, if the benzothienobenzothiophene system organicmaterial in the present disclosure is used as a p-type semiconductormaterial, and fullerene (C60, C70) is used as an n-type semiconductormaterial, then, as compared with the past image pickup element orphotoelectric conversion element, a higher quantum efficiency (externalconversion efficiency, EQE), and higher carrier mobility can beattained. Although fullerene has a high electron transport property interms of the n-type semiconductor material, fullerene has high symmetry(soccer-ball-shape) in the three-dimensional direction, and thecharacteristics of the image pickup element or the photoelectricconversion element largely depends on the character of the p-typesemiconductor material with which fullerene is combined. The combinationof the benzothienobenzothiophene system organic material and fullerenein the present disclosure is a very preferable combination. It should benoted that although the organic semiconductors are classified into ap-type and an n-type in many cases, the p-type means that it readilytransports the holes, and the n-type means that it readily transportsthe electrons. Thus, the organic semiconductors are not limited to theinterpretation that the organic semiconductor has the holes or electronsas the majority carrier in the thermal excitation like the inorganicsemiconductors. The group or the like contained in a fullerenederivative can include: a halogen atom; a straight chain, branched orcyclic alkyl group or phenyl group; a group having a straight chain orcondensed aromatic compound; a group having a halide; a partialfluoroalkyl group; a perfluoroalkyl group; a cyrilalkyl group; acyrilalkoxy group; an allycyril group; an allylsulfanyl group; analkylsulfide group; an allylsulphonyl group; an alkylsulphonyl group; anallylsulfany group; an alkylsulfide group; an amino group; an alkylaminogroup; an allylamino group; a hydroxy group; an alkoxy group; anacylamino group; an acyloxy group; a carbonyl group; a carboxy group; acarboxythoamido group; a carboalkoxy group; an acyl group; a sulfonylgroup; a cyano group; a nitro group; a group having a chalcogenide; aphosphine group; a phosphonate group; and a derivative thereof.

Alternatively, in the image pickup element, etc. of the presentdisclosure,

the organic photoelectric conversion layer further includes a secondorganic semiconductor material and a third semiconductor material,

the second organic semiconductor material includes fullerene or afullerene derivative,

a value μ₃ of a line absorption coefficient in a local maximum opticalabsorption wavelength in a visible light region of the third organicsemiconductor material can be configured to be larger than a value μ₁ ofa line absorption coefficient in a local maximum optical absorptionwavelength in a visible light region of the first organic semiconductormaterial, and configured to be larger than a value μ₂ of a lineabsorption coefficient in a local maximum optical absorption wavelengthin a visible light region of the second organic semiconductor material.As a result, the light (photons) made incident to the organicphotoelectric conversion layer can be selectively absorbed by the thirdorganic semiconductor material having the larger line absorptioncoefficient. After the photons absorbed in the third organicsemiconductor material turn into excitons, the resulting excitons causethe exciton separation in an interface between the first organicsemiconductor material and the third organic semiconductor material, oran interface between the second organic semiconductor material and thethird organic semiconductor material, or an interface between the firstorganic semiconductor material and the second organic semiconductormaterial, and the third organic semiconductor material, thereby enablingthe carriers of the holes and the electrons to be generated. Thecarriers thus generated (holes and electrons) are efficientlytransmitted to electrodes based on the high hole mobility which thefirst organic semiconductor material has, and the high electron mobilitywhich the second organic semiconductor material has. Then, the holes andthe electrons which reach the respective electrodes are detected in theform of photocurrents. A generation probability of the photocurrent tothe incident photons is generally called the photoelectric conversionefficiency. Therefore, by regulating the values μ₁, μ₂, and μ₃ of theline absorption coefficients, the light can be selectively, effectivelyabsorbed in the third organic semiconductor material. The highphotoelectric conversion efficiency can be attained in accordance withsuch a principle. The line absorption coefficient can be calculatedbased on such a method as to obtain an absorption rate (%) of thephotons to the wavelength by using an ultraviolet and visiblespectrophotometer, and obtain a thickness by using a stylus-typeroughness meter in a thin film of the organic semiconductor material.Then, in such a constitution, it is possible to adopt a constitution inwhich the excitons generated by the optical absorption in the thirdorganic semiconductor material are subjected to the exciton separationin the interface between the first organic semiconductor material andthe second organic semiconductor material, and the third organicsemiconductor material, or both the interfaces between the organicsemiconductor materials selected from two of the first organicsemiconductor material, the second organic semiconductor material, andthe third organic semiconductor material or the excitons generated bythe optical absorption in the third organic semiconductor material aresubjected to the exciton separation in the interface of one kind oforganic semiconductor material selected from the first organicsemiconductor material, the second organic semiconductor material, andthe third organic semiconductor material. Then, in those constitutions,it is possible to adopt a constitution in which the exciton chargeseparation rate at which the excitons are subjected to the excitonseparation is 1×10¹⁰ s⁻¹ or more. Moreover, in those constitutions, itis possible to adopt a constitution in which the organic photoelectricconversion layer has a local maximum optical absorption wavelength inthe range of 450 nm or more to 650 nm or less. Furthermore, in thoseconstitutions, it is possible to adopt a constitution in which the thirdorganic semiconductor material includes subphthalocyanine expressed bythe following structural formula (10), and a subphthalocyanine systemderivative. Here, specifically, the subphthalocyanine system derivativecan include the following structural formula (11). More specifically,the subphthalocyanine system derivative can include the followingstructural formula (12) abbreviated as “SubPc-Cl,” the followingstructural formula (13) abbreviated as “SubPc-F,” the followingstructural formula (14) abbreviated as “SubPc-OC6F5,” the followingstructural formula (15) abbreviated as “F12SubPc-Cl,” the followingstructural formula (16) abbreviated as “F6SubPc-Cl,” the followingstructural formula (17) abbreviated as “F6SubPc-F,” and the followingstructural formula (18) abbreviated as “F6SubPc-OC6F5.” Here, since thesubphthalocyanine system derivative has the high line absorptioncoefficient, the subphthalocyanine system derivative is used, therebyenabling the third organic semiconductor material to more selectivelyabsorb the light to generate the excitons. Furthermore, in thoseconstitutions, it is possible to adopt a constitution in which:

the organic photoelectric conversion layer further includes a fourthorganic semiconductor material; and

the fourth organic semiconductor material is provided with a motherskeleton similar to that of the first organic semiconductor material, orthe fourth organic semiconductor material has the same mother skeletonas that of the second organic semiconductor material or the thirdorganic semiconductor material, and is provided with a differentsubstituent. By adopting such a constitution, the spectralcharacteristics of the visible region can be made more readily desiredcharacteristics. However, if the fourth organic semiconductor materialhas any of the hole transport ability which the first organicsemiconductor material has, the high electron transport ability whichthe second organic semiconductor material has, and the large lineabsorption coefficient which the third organic semiconductor materialhas, then, a molecular structure is not especially limited.

The fourth organic semiconductor material provided with the motherskeleton similar to that of the first organic semiconductor material caninclude the following structural formula (101) and structural formula(102). A concrete example of the structural formula (101) and structuralformula (102) can include a structural formula (103) to a structuralformula (115).

Here, in the structural formula (101) and the structural formula (102)as an acenedichalcogenophen derivative, Ar¹ represents any of acenegroup including a benzene ring, a naphthalene ring, an anthracene ring,and the like, and Y represents an oxygen atom, a sulfur atom or aselenium atom. In addition, two different atoms other than a carbon atommay be contained in a five-membered ring. Specifically, an acenethiazolederivative (S and N) and an oxazole derivative can be exemplified.

Here, in a structural formula (103) to a structural formula (111), Yrepresents an oxygen atom, a sulfur atom or a selenium atom.

Here, in a structural formula (112) to a structural formula (115), Zrepresents an oxygen atom, a sulfur atom or a selenium atom.

Here, the structural formula (1) and the structural formula (2) as thebenzothienobenzothiophene system organic material are a part of achalcogenochalcogenphene derivative. Ar₁ and Ar₂ represent any of acenegroup including a benzene ring, a naphthalene ring, an anthracene ring,and the like (or, Ar₁ and Ar₂ represent the same fused ring, andspecifically, represent any of acene group including a benzene ring, anaphthalene ring, an anthracene ring, and the like). Y represents anoxygen atom, a sulfur atom or a selenium atom. In addition, twodifferent atoms other than a carbon atom may be contained in afive-membered ring. Specifically, an acenethiozole derivative (S and N)and an oxazole derivative can be exemplified. It is known that a groupof these materials exhibits the high hole mobility (for example, referto JP 2014-036039A).

In addition, the fourth organic semiconductor material having the samemother skeleton as that of the second organic semiconductor material,and provided with a substituent different therefrom can includePhenyl-Butyric Acid Methyl Ester (PCBM) of C60 or C70. In addition, thefourth organic semiconductor material having the same mother skeleton asthat of the third organic semiconductor material, and provided with asubstituent different therefrom can include structures of the structuralformula (10) to the structural formula (25) (however, having thestructure different from that of the third organic semiconductormaterial).

Alternatively, in the image pickup element, etc. of the presentdisclosure, it is possible to adopt a constitution in which the organicphotoelectric conversion layer further includes a second organicsemiconductor material and a third organic semiconductor material;

an area of a portion in which an energy distribution state density ofHOMO or LUMO of the second organic semiconductor material, and an energydistribution state density of HOMO or LUMO of the third organicsemiconductor material overlap each other is 0.15 meV or more. Then, inthis case, it is possible to adopt a constitution in which an energydistribution σ of the third organic semiconductor material or an energydistribution σ of the second organic semiconductor material is 70 meV orless. Furthermore, in these cases, it is possible to adopt aconstitution in which the second organic semiconductor material, forexample, includes fullerene or the fullerene derivative described above.Furthermore, in these cases, it is possible to adopt a constitution inwhich the third organic semiconductor material, for example, includes asubphthalocyanine system derivative represented by the structuralformula (10) to the structural formula (18).

However, X and R₁ to R₁₂ are each at least one group independentlyselected from the group consisting of a hydrogen atom; a halogen atomcontaining chlorine and fluorine; or a straight chain, branched orcyclic alkyl group or a phenyl group; a straight chain or fused aromaticring; a partial fluoroalkyl group; a perfluoroalkyl group; a silylalkylgroup; a cyrilalkoxy group; an allylsilyl group, a thioalkyl group; athioaryl group; an allylsulfanyl group; an alkylsulfanyl group; an aminogroup; an alkylamino group; an allylamino group; a hydroxyl group; analkoxy group; an acylamino group; an acyloxy group; a carboxy group; acarboxythoamido group; a carboalkoxy group; an acyl group; a sulfonylgroup; a cyano group; and a nitro group.

In the image pickup element, etc. of the present disclosure includingthe various preferred forms and constitutions described so far, it isdesirable that the hole mobility of the first organic semiconductormaterial is 1×10⁻⁵ cm²/V·s or more, preferably 1×10⁻⁴ cm²/V·s or more,and more preferably 1×10⁻² cm²/V·s or more.

In the image pickup element, etc. of the present disclosure includingthe various preferred forms and constitutions described so far, a firstelectrode and a second electrode can be configured to include atransparent conductive material(s). Alternatively, one of the firstelectrode and the second electrode can be configured to include atransparent conductive material, and the other can be configured toinclude a metallic material.

In the image pickup element, etc. of the present disclosure includingthe various preferred forms and constitutions described so far, it ispreferable that the electrode on the light incidence side is configuredto include a transparent conductive material. Such an electrode isreferred to as “a transparent electrode.” Here, an indium-tin oxide(including ITO, Sn-doped In₂O₃, crystalline ITO, and amorphous ITO), IFO(F-doped In₂O₃), a tin oxide (SnO₂), ATO (Sb-doped SnO₂), FTO (F-dopedSnO₂), a zinc oxide (including Al-doped ZnO, B-doped ZnO, and Ga-dopedZnO), an indium oxide-a zinc oxide (IZO), a titanium oxide (TiO₂), aspinel-type oxide, and an oxide having a YbFe₂O₄ structure canexemplified as the transparent conductive material constituting thetransparent electrode. A method of forming the transparent electrode,although depending on the material constituting the transparentelectrode, can include a physical vapor deposition method (PVD method)such as a vacuum evaporation method, a reactive evaporation method,various sputtering methods, an electron beam evaporation method, and anion plating method, various chemical vapor deposition methods (CVDmethods) including a pyrosol process, a method of thermally decomposingan organic metallic compound, a spraying method, a dipping method, andan MOCVD method, a nonelectrolytic plating method, and an electrolyticplating method. In some cases, as described above, the other electrodemay also be configured to include a transparent conductive material.

In the case where the transparency is unnecessary, when as far as theconductive material constituting the first electrode or the secondelectrode, the first electrode or the second electrode is made tofunction as a cathode electrode (cathode), that is, function as anelectrode from which the holes are taken out, the cathode electrodepreferably includes a conductive material having a high work function(for example, Φ=4.5 eV to 5.5 eV). Specifically, it is possible toexemplify gold (Au), silver (Ag), chromium (Cr), nickel (Ni), palladium(Pd), platinum (Pt), iron (Fe), iridium (Ir), germanium (Ge), Osmium(Os), rhenium (Re), and tellurium (Te). On the other hand, when thefirst electrode or the second electrode is made to function as an anode,that is, function as an electrode from which the electrons are takenout, the anode preferably includes a conductive material having a lowwork function (for example, Φ=3.5 eV to 4.5 eV). Specifically, it ispossible to give an alkaline a metal (such as Li, Na, or K) and afluoride or oxide thereof, an alkaline earth metal (such as Mg or Ca)and a fluoride or oxide thereof, aluminum (Al), zinc (Zn), tin (Sn),thallium (Tl), a sodium-kalium alloy, an aluminum-lithium alloy, amagnesium-silver alloy, a rare earth metal such as indium or ytterbium,or an alloy thereof. Alternatively, the material constituting the firstelectrode or the second electrode can include a metal such as platinum(Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni), aluminum(Al), silver (Ag), tantalum (Ta), tungsten (W), copper (Cu), titanium(Ti), indium (In), tin (Sn), iron (Fe), cobalt (Co), and molybdenum(Mo), or conductive materials such as alloys containing these metalelements, conductive particles including these metals, conductiveparticles of alloys containing these metals, polysilicon containing animpurity, a carbon system material, a semiconductor oxide, a carbonnanotube, and graphene. In addition, it is possible to adopt thelaminated structure of the layers containing these elements. Moreover,the materials constituting the first electrode and the second electrodecan include a material (conductive polymer) such as poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid [PEDOT/PSS]. In addition,these conductive materials may be mixed with binder (polymer) to producepaste or ink which may be in turn cured to be used as the electrode.

A method of forming the first electrode and the second electrode,although depending on the materials constituting those, can include acombination of any one of various kinds of PVD methods which will bedescribed later; various kinds of CVD methods including an MOCVD method;various paint-on method which will be described later; a lift-offmethod; a sol-gel method; an electrodeposition method; a shadow maskmethod; plating methods such as an electrolytic plating method and anonelectrolytic plating method or a combination thereof; and a sprayingmethod, and a patterning technique as may be necessary. The surfaces ofthe first electrode and the second electrode can be processed withoxygen plasma, argon plasma, nitrogen plasma, ozone or the like. Thesepieces of processing can be carried out irrespective of presence orabsence of a coating layer (which will be described later), or before orafter the coating.

Moreover, in the image pickup element, etc. of the present disclosureincluding the preferred forms and constitutions described so far, it ispossible to adopt a constitution in which a wavelength of an opticalabsorption peak in an optical absorption spectrum of the organicphotoelectric conversion layer falls within a visible light region.Moreover, in the image pickup element, etc. of the present disclosureincluding the preferred forms and constitutions described so far, it ispossible to adopt a constitution in which an optical absorption spectrumof the organic photoelectric conversion layer has one local maximumvalue in the visible light region.

Moreover, in the image pickup element, etc. of the present disclosureincluding the preferred forms and constitutions described so far, it isdesirable that an absorption coefficient α (cm⁻¹) of the organicphotoelectric conversion layer is 1×10⁵ or more, preferably 1.5×10⁵ ormore, more preferably 2×10⁵ or more, and still more preferably 2.5×10⁵or more. In addition, in the image pickup element, etc. of the presentdisclosure including the preferred forms and constitutions described sofar, a sublimation temperature under the atmosphere of the material(s)constituting the organic photoelectric conversion layer is desirably250° C. or more. In addition, 2,000 or less, preferably 500 to 1,500,and more preferably 500 to 1,000 can be exemplified as a molecularweight of the whole organic photoelectric conversion layer constitutingthe image pickup element, etc. of the present disclosure.

In the image pickup element, etc. of the present disclosure, a p-typeorganic optical absorption material or organic transparent material,and/or an n-type organic optical absorption material or organictransparent material may be further contained in the organicphotoelectric conversion layer. The p-type organic optical absorptionmaterial organic transparent material, and/or an n-type organic opticalabsorption material or organic transparent material can include anaromatic monocyclic system compound, an aromatic fused ring systemcompound, a heteromonocyclic system compound, a fused heterocyclicsystem compound, a polymethine system compound, a n conjugatedlow-molecular-weight system compound, a carbonium compound, a styrylsystem compound, a stilbene system compound, a metal complex systemcompound, a n conjugated polymer system compound, a σ conjugated systemcompound, a dye-containing polymeric system compound, and a polymercomplex system compound. That is to say, the organic photoelectricconversion layer can include forms such as:

(A) A form in which a benzothienobenzothiophene system organic materialhaving a p-type in the present disclosure is contained(B) A form in which a benzothienobenzothiophene system organic materialhaving a p-type in the present disclosure, and fullerene or a fullerenederivative each having a p-type in the present disclosure is contained(C) A form in which a benzothienobenzothiophene system organic materialhaving a p-type in the present disclosure, and a fullerene derivativeeach having a p-type in the present disclosure, and a p-type organicoptical absorption material or organic transparent material, and/or ann-type organic optical absorption material or organic transparentmaterial are contained(D) A form in which a benzothienobenzothiophene system organic materialhaving a p-type in the present disclosure, and fullerene or a fullerenederivative each having a p-type in the present disclosure, and a p-typeorganic optical absorption material or organic transparent material,and/or an n-type organic optical absorption material or organictransparent material are contained(E) A form in which an acenedichalcogenophene system organic materialhaving a p-type is contained(F) A form in which an acenedichalcogenophene system organic materialhaving a p-type, and fullerene or a fullerene derivative having a p-typeare contained.(G) A form in which an acenedichalcogenophene system organic materialhaving a p-type, and fullerene or a fullerene derivative having ap-type, and a p-type organic optical absorption material or organictransparent material, and/or an n-type organic optical absorptionmaterial or organic transparent material are contained(H) A form in which an acenedichalcogenophene system organic materialhaving a p-type, and a p-type organic optical absorption material ororganic transparent material, and/or an n-type organic opticalabsorption material or organic transparent material are contained. Itshould be noted that hereinafter, these eight forms are generallyreferred to as “a p-type organic material in the present disclosure” insome cases.

The aromatic monocyclic system compound, specifically, can include atriallyl amine system compound and a derivative thereof, a biphenylsystem compound and a derivative thereof, and a diphenoquinone systemcompound and a derivative thereof.

The aromatic fused ring system compound, specifically, can include anacene system compound represented by naphthalene, anthracene, andpentacene and a derivative thereof, a rubrene system compound and aderivative thereof, a phenanthrene system compound and a derivativethereof, a fluoranthene system compound and a derivative thereof, atriphenylene system compound and a derivative thereof, a pyrene systemcompound and a derivative thereof, a chrysene system compound and aderivative thereof, a perylene system compound and a derivative thereof,a coronene system compound and a derivative thereof, an indene systemcompound and a derivative thereof, a bianthyl system compound and aderivative thereof, a toriantoriren system compound and a derivativethereof, a fluoranthene system compound and a derivative thereof, anaceanthrylene system compound and a derivative thereof, a pentaphenesystem compound and a derivative thereof, a tetra-phenylene systemcompound and a derivative thereof, a peropyrene system compound and aderivative thereof, a terylene system compound and a derivative thereof,a bisanthrylene system compound and a derivative thereof, aquaterterylene system compound and a derivative thereof, an indanesystem compound and a derivative thereof, and a rubicene system compoundand a derivative thereof.

The heteromonocylic system compound, specifically, can include athiophene system compound and a derivative thereof, a pyrazoline systemcompound and a derivative thereof, an azole system compound and aderivative thereof, an oxazole system compound and a derivative thereof,an oxadiazole system compound and a derivative thereof, a pyrane systemcompound and a derivative thereof, a thiopyrane system compound and aderivative thereof, a pyrazine system compound and a derivative thereof,a thiazole system compound and a derivative thereof, a pyrrole systemcompound and a derivative thereof, a triazole system compound and aderivative thereof, a squarylium system compound and a derivativethereof, a lactam system compound and a derivative thereof, anazobenzene system compound and a derivative thereof, a quinone systemcompound and a derivative thereof, a furan system compound and aderivative thereof, an azole system compound and a derivative thereof, apyrrolidone system compound and a derivative thereof, a silole systemcompound and a derivative thereof, an oxazoline system compound and aderivative thereof, an imidazole system compound and a derivativethereof, a pyrazoline system compound and a derivative thereof, apyridine system compound and a derivative thereof, a bipyridine systemcompound and a derivative thereof, a pyridazine system compound and aderivative thereof, a dithiol system compound and a derivative thereof,and a dioxyborane system compound and a derivative thereof.

The fused heterocyclic system compound, specifically, can include apyrrolopyrrole system compound and a derivative thereof, a diazabicyclosystem compound and a derivative thereof, a phthalide system compoundand a derivative thereof, a benzoxazole system compound and a derivativethereof, a benzothiophene system compound and a derivative thereof, abenzothiazole system compound and a derivative thereof, an indole systemcompound and a derivative thereof, an imidazopyridine system compoundand a derivative thereof, a benzoazole system compound and a derivativethereof, a benzopyran system compound and a derivative thereof, acoumarin system compound and a derivative thereof, a chromone systemcompound and a derivative thereof, an azacoumarin system compound and aderivative thereof, a quinolone system compound and a derivativethereof, a benzoxazine system compound and a derivative thereof, aphthalazine system compound and a derivative thereof, a quinazolinesystem compound and a derivative thereof, a quinoxalline system compoundand a derivative thereof, a pyrimidopyrimidine system compound and aderivative thereof, a dibenzofuran system compound and a derivativethereof, a carbazole system compound and a derivative thereof, apyrazoquinoline system compound and a derivative thereof, anaphthalimide system compound and a derivative thereof, a benzquinolinesystem compound and a derivative thereof, a phenanthridinne systemcompound and a derivative thereof, a phenanthroline system compound anda derivative thereof, a phenazine system compound and a derivativethereof, a pyridoquinoline system compound and a derivative thereof, adipyrimidopyrimidine system compound and a derivative thereof, ateazaflavin system compound and a derivative thereof, a dioxazine systemcompound and a derivative thereof, a pyrimidoquinazoline system compoundand a derivative thereof, a phenanthazole system compound and aderivative thereof, a pyridoimidazoquinoxaline system compound and aderivative thereof, a benzophenoxazone system compound and a derivativethereof, a thioepindolidone system compound and a derivative thereof, anepindolidione system compound and a derivative thereof, athioquinacridone system compound and a derivative thereof, aquinacridone system compound and a derivative thereof, atriphenodioxazine system compound and a derivative thereof, a perinonesystem compound and a derivative thereof, a Peckman dye system compoundand a derivative thereof, a naphthyridine system compound and aderivative thereof, a benzofuropyrazine system compound and a derivativethereof, an azathioxantene system compound and a derivative thereof, andan azanaphthofluoranthene system compound and a derivative thereof.

The polymethine system compound, specifically, can include a methinesystem compound and a derivative thereof, a polymethine system compoundand a derivative thereof, a merocyanine system compound and a derivativethereof, a hemicyanine system compound and a derivative thereof, astreptocyanine system compound and a derivative thereof, an oxanolsystem compound and a derivative thereof, a pyrylium system compound anda derivative thereof, and a cyanine system compound and a derivativethereof. More specifically, the polymethine system compound can includea phthalocyanine system compound and a derivative thereof, asubphthalocyanine system compound and a derivative thereof, and adipyrine system compound and a derivative thereof.

The π conjugated low-molecular-weight system compound, specifically, caninclude a dicyanomethylene system compound and a derivative thereof, anda malenonitrile system compound and a derivative thereof. The carboniumsystem compound, specifically, can include a xanthen system compound anda derivative thereof, a rhodamine system compound and a derivativethereof, an acridine system compound and a derivative thereof, athioxanthene system compound and a derivative thereof, and an acridonesystem compound and a derivative thereof. The styryl system compound,specifically, can include a monofunctional styryl system compound and aderivative thereof, a polyfunctional styryl system compound and aderivative thereof, and a tetrabuthylbutadiene system compound and aderivative thereof. The stilbene system compound, specifically, caninclude a stilbene system compound and a derivative thereof, anazomethine system compound and a derivative thereof, an azobenzenesystem compound and a derivative thereof, and a fluorossein systemcompound and a derivative thereof. The metal complex system compound,specifically, can include a Schiff base system compound and a derivativethereof, a porphyrin system compound ad a derivative thereof, ametalloporphyrin system compound and a derivative thereof, ametallodipyrine system compound and a derivative thereof, a lanthanoidsystem compound and a derivative thereof, a metallophthalocyanine systemcompound and a derivative thereof, and a hydroxyquinolilato complexsystem compound and a derivative thereof. More specifically, the metalcomplex system compound can include a tris(8-quinolinolato) metalcomplex represented by tris(8-quinolinolato) aluminum, and a derivativethereof. The n conjugated polymer system compound, for example, caninclude a PPV system compound and a derivative thereof, anoligothiophene system compound and a derivative thereof, a polythiophenesystem compound and a derivative thereof, and a polyalkylfluorene systemcompound and a derivative thereof. The σ conjugated system compound,specifically, can include an oligosilane system compound and aderivative thereof, and a polysilane system compound and a derivativethereof. In addition, the σ conjugated system compound can include,specifically, as other compounds, an indigo compound and a derivativethereof, a thioindigo compound and a derivative thereof, a spirancompound and a derivative thereof, a silane system compound and aderivative thereof, and a boron system compound and a derivativethereof.

In the image pickup element, etc. of the present disclosure, it ispossible to adopt a constitution in which a first buffer layer/anorganic photoelectric conversion layer/a second buffer are formedbetween the first electrode and the second electrode. Specifically, forexample,

[First Constitution]

It is possible to adopt a constitution of:a first buffer layeran organic photoelectric conversion layer

a p-type organic material of the present disclosure, or

a mixed material of a p-type organic material of the present disclosureand an n-type organic transparent material, or

a bulk-hetero layer

a second buffer layer. The respective layers may be a laminatedstructure of a plurality of material layers or a mixed layer of aplurality of materials as long as the layers have the respective desiredfunctions. In some cases, the first buffer layer can be omitted. Inaddition, “the bulk-hetero layer” is a layer including a mixed layer ofa p-type organic optical absorption material and an n-type organicoptical absorption material. It should be noted that the first electrodemay be located below and the second electrode may be located above, orthe second electrode may be located below and the first electrode may belocated above. In addition, the lamination order of the layers betweenthe first electrode and the second electrode can also be verticallyreversed. This applies to the following.

An n-type organic dye material or organic transparent materialconstituting the first buffer layer can include an aromatic ring systemcompound and a hydrazine system compound in addition to the n-typeorganic optical absorption material or organic transparent materialdescribed above. The aromatic ring system compound, specifically, caninclude a monoamine system compound and a derivative thereof, analkylene bond system compound and a derivative thereof, an allylenesystem compound and a derivative thereof, a phenylenediamine systemcompound and a derivative thereof, and a star-burst system compound anda derivative thereof. In addition, other components, specifically, caninclude metals represented by Ca, Mg, Li, Ag, and Al, and inorganiccompounds of these metals (specifically, halides, oxides and complexcompounds of these metals).

The organic photoelectric conversion layer may include the followingmaterials in addition to the p-type organic materials of the presentdisclosure. That is to say, the organic photoelectric conversion layermay include an aromatic ring system compound, a hydrozone systemcompound, an alicyclic system compound, an aromatic ring systemcompound, and a heterocyclic ring system compound. The aromatic ringsystem compound, specifically, can include a monoamine system compoundand a derivative thereof, an alkylene bond system compound and aderivative thereof, an allylene system compound and a derivativethereof, a phenylenediamine system compound and a derivative thereof,and a star-burst system compound and a derivative thereof. The alicyclicsystem compound, specifically, can include a cyclopentadiene systemcompound and a derivative thereof. The aromatic ring system compound caninclude a tetraphenylbutadien system compound and a derivative thereof,a p-phenylene system compound and a derivative thereof, and afluoronylidenemethane system compound and a derivative thereof. Theheterocyclic ring system compound, specifically, can include atiadiazopyridine system compound and a derivative thereof, apyrrolopyridine system compound and a derivative thereof, agermacyclopentadiene system compound and a derivative thereof, abenzazole system compound and a derivative thereof, and a terryleneimidosystem compound and a derivative thereof. The n-type organic transparentmaterial included in the organic photoelectric conversion layer caninclude the n-type organic optical absorption material or organictransparent material described above.

The p-type organic dye material or organic transparent materialconstituting the second buffer layer can include an alicyclic systemcompound, an aromatic ring system compound, and a heterocyclic systemcompound in addition to the p-type organic optical absorption materialor organic transparent material described above. The alicyclic systemcompound, specifically, can include a cyclopentadiene system compoundand a derivative thereof. The aromatic ring system compound can includea tetraphenylbutadien system compound and a derivative thereof, ap-phenylene system compound and a derivative thereof, and afluoronylidenemethane system compound and a derivative thereof. Theheterocyclic system compound, specifically, can include atiadiazophridine system compound and a derivative thereof, apyrrolopyridine system compound and a derivative thereof, agermacyclopentadiene system compound and a derivative thereof, abenzazole system compound and a derivative thereof, and a terryleneimidosystem compound and a derivative thereof.

Alternatively, in the image pickup element, etc. of the presentdisclosure, it is possible to adopt a form in which the first bufferlayer/the n-type organic material layer/the organic photoelectricconversion layer/the p-type organic material layer/the second bufferlayer are formed between the first electrode and the second electrode.Specifically, for example, it is possible to adopt such a constitutionthat:

[Second Constitution]

a first buffer layeran n-type organic material layeran organic photoelectric conversion layer

a p-type organic material of the present disclosure, or

a mixed material of the p-type organic material of the presentdisclosure and the n-type organic transparent material, or

a bulk-hetero layer

a p-type organic material layera second buffer layer.The layers may be a laminated structure of a plurality of materiallayers or a mixed layer of a plurality of materials as long as thelayers have the respective desired functions.

It is only necessary that the first buffer layer, the organicphotoelectric conversion layer, and the second buffer layer have thesimilar constitution to that of the first buffer layer, the organicphotoelectric conversion layer, and the second buffer layer which aredescribed in [First Structure].

The organic dye material or organic transparent material constitutingthe n-type organic material can include an aromatic ring system compoundand a hydrazone system compound in addition to the n-type organicoptical absorption material or organic transparent material describedabove. The aromatic ring system compound, specifically, can include amonoamine system compound and a derivative thereof, an alkylene bondsystem compound and a derivative thereof, an allylene system compoundand a derivative thereof, a phenylenediamine system compound and aderivative thereof, and a star-burst system compound and a derivativethereof.

The organic dye material or organic transparent material constitutingthe p-type organic material layer can include the similar material tothat of the second buffer layer described in [First Structure].

Alternatively, in the image pickup element, etc. of the presentdisclosure, it is possible to adopt a form in which a hole blockinglayer/an organic photoelectric conversion layer/an electron blockinglayer are formed between the first electrode and the second electrode.Specifically, for example, it is possible to adopt such a constitutionthat:

[Third Constitution]

a hole blocking layeran organic photoelectric conversion layer

a p-type organic material of the present disclosure, or

a mixed material of the p-type organic material of the presentdisclosure and an n-type organic transparent material, or

a bulk-hetero layer

an electron blocking layer.The layers may be a laminated structure of a plurality of materiallayers or a mixed layer of a plurality of materials as long as thelayers have the respective desired functions.

The p-type organic dye material or organic transparent materialconstituting the hole blocking layer can include the similar material tothat of the second buffer layer described in [First Structure]. Inaddition, other compounds, specifically, can include metals representedby Ca, Mg, Li, Ag, and Al, and inorganic compounds of these metals(specifically, halides, oxides and complex compounds of these metals).

The n-type organic dye material or organic transparent materialconstituting the electron blocking layer can include the similarmaterial to that of the first buffer layer described in [FirstStructure].

Alternatively, in the image pickup element, etc. of the presentdisclosure, it is possible to adopt either a form in which a laminatedstructure of an n-type first organic photoelectric conversion layer anda p-type second organic photoelectric conversion layer (including thep-type organic material of the present disclosure) is formed between thefirst electrode/the first buffer layer and the second buffer layer/thesecond electrode, or a form in which this laminated structure isrepetitively formed. The materials constituting these layers can includethe various kinds of materials described so far.

In addition, it is possible to adopt either a form in which a laminatedstructure of the n-type first organic photoelectric conversion layer,the bulk-hetero layer, and the p-type second organic photoelectricconversion layer (including the p-type organic material of the presentdisclosure) is formed between the first electrode/the first buffer layerand the second buffer layer/the second electrode, or a form in whichthis laminated structure is repetitively formed.

In addition, it is also possible to adopt the so-called tandem structurein which the image pickup element according to the first aspect and thesecond aspect of the present disclosure having a sensitivity to a redcolor, the image pickup element according to the first aspect and thesecond aspect of the present disclosure having a sensitivity to a greencolor, and the image pickup element according to the first aspect andthe second aspect of the present disclosure having a sensitivity to ablue color are laminated on one another.

In the image pickup element, etc. of the present disclosure includingthe predetermined forms and constitutions described so far, it ispossible to adopt a constitution in which:

the first electrode including the transparent conductive material isformed on a transparent substrate,

the organic photoelectric conversion layer is formed on the firstelectrode, and

the second electrode is formed on the organic photoelectric conversionlayer. Alternatively, it is possible to adopt a constitution in which:

the first electrode is formed on a substrate,

the organic photoelectric conversion layer is formed on the firstelectrode, and the second electrode including the transparent conductivematerial is formed on the organic photoelectric conversion layer. Here,although the first electrode and the second electrode are separated fromeach other, such a separation state can include a form in which thesecond electrode is formed above the first electrode.

A method of depositing the organic photoelectric conversion layer caninclude a paint-on method, a PVD method, and various CVD methodsincluding an MOCVD method. Here, the paint-on method, specifically, canexemplify a spin coating method; an immersion method; a casting method;various printing methods such as a screen printing method, an inkjetprinting method, an offset printing method, and a gravure printingmethod; a stamping method, a spraying method; and various coatingmethods such as an air doctor coater method, a blade coaster method, arod coater method, a knife coater method, a squeeze coater method, areverse roll coater method, a transfer roll coater method, a gravurecoater method, a kiss coater method, a cast coater method, a sprayingcoater method, a slit orifice coater method, and a calendar coatermethod. It should be noted that the paint-on method can exemplify anorganic solvent having nonpolar or low polar such as toluene,chloroform, hexane or ethanol as a solvent, but the paint-on method isby no means limited thereto. In addition, the PVD method can include:various vacuum evaporation methods such as an electron beam heatingmethod, a resistance heating method, and flash evaporation; a plasmaevaporation method; various sputtering methods such as a diodesputtering method, a DC sputtering method, a DC magnetron sputteringmethod, a high-frequency sputtering method, a magnetron sputteringmethod, an ion beam sputtering method, and a bias sputtering method; andvarious ion plating methods such as a direct current (DC) method, an RFmethod, a multi-cathode method, an activation reaction method, anelectric field vapor deposition method, a high-frequency ion platingmethod, and a reactive ion plating method. Alternatively, when the imagepickup elements are integrated with one another in order to configurethe solid-state image pickup device, it is also possible to adopt amethod of forming a pattern based on a pulse laser deposition method(PLD method).

It is possible to exemplify that the thickness of the organicphotoelectric conversion layer, not limited to, for example, is in therange of 1×10⁻⁸ m to 7×10⁻⁷ m, preferably in the range of 2.5×10⁻⁸ m to5×10⁻⁷ m, more preferably in the range of 2.5×10⁻⁸ m to 5×10⁻⁷ m, andstill more preferably in the range of 1×10⁻⁷ m to 3×10⁻⁷ m.

The substrate can include organic polymer (having a form of a polymermaterial such as a plastic film, a plastic sheet, or a plastic substratehaving the flexibility and including a polymer material) exemplified bypolymethylmethacrylate (polymethylmethacrylate, PMMA), polyvinyl alcohol(PVA), polyvinyl phenol (PVP), polyether sulfone (PES), polyimide,polycarbonate (PC), polyethylene-telephthalate (PET), andpolyethylene-naphthalate (PEN), or can include mica. When the substrateincluding such a polymer material having the flexibility is used, forexample, the incorporation or integration of the image pickup element,etc. in or with the electronic apparatus having a curved surface shapebecomes possible. Alternatively, the substrate can include various glasssubstrates, various glass substrates on surfaces of which insulatingfilms are formed, a quartz substrate, a quartz substrate on a surface ofwhich an insulating film is formed, a silicon substrate, a siliconsubstrate on a surface of which an insulating film is formed, andmetallic substrates including various alloys or various metals such as astainless steel. It should be noted that the insulating film caninclude: a silicon oxide system material (such as SiO_(X) orspin-on-glass (SOG)); a silicon nitride (SiN_(Y)); a silicon oxynitride(SiON); an aluminum oxide (Al₂O₃); and a metal oxide or a metal salt. Inaddition, it is also possible to use conductive substrates (a substrateincluding a metal such as gold, or aluminum, or a substrate includinghighly oriented graphite) on the surfaces of which these insulatingfilms are formed. Although the surface of the substrate is desirablysmooth, it may have such roughness as not to exert a bad influence onthe characteristics of the organic photoelectric conversion layer. Asilanol derivative may be formed on the surface of the substrate byusing a silane coupling method, a thin film including a thiolderivative, a carboxylic acid derivative, a phosphoric acid derivativeor the like may be formed on the surface of the substrate by using a SAMmethod or the like, and a thin film including an insulating metal saltor metal complex may also be formed on the surface of the substrate byusing the CVD method or the like, thereby enhancing the adhesivenessbetween the first electrode or the second electrode, and the substrate.The transparent substrate means a substrate including a material whichdoes not excessively absorb the light made incident to the organicphotoelectric conversion layer through the substrate.

In accordance with circumstances, the electrode and the organicphotoelectric conversion layer may be covered with a covering layer. Amaterial constituting the coating layer can include: not only aninorganic insulating material exemplified by a metal oxidehigh-dielectric insulating film such as a silicon oxide system material;a silicon nitride (SiN_(Y)); and an aluminum oxide (Al₂O₃), but also anorganic insulating material (organic polymer) exemplified bypolymethylmethacrylate (PMMA); polyvinyl phenol (PVP); polyvinyl alcohol(PVA); polyimide; polycarbonate (PC); polyethylene-telephthalate (PET);polystyrene; a silanol derivative (silane coupling agent) such asN-2(aminoethyl)3-aminopropyltrimethoxysilane (AEAPTMS),3-mercaptoprophyltrimethoxysilane (MPTMS), or octadecyltrichlorosilane(OTS); and a straight chain hydrocarbon class having a functional groupcapable of being coupled to the electrode at one end of octadecanethiol,dodecylisocyanade or the like, and can also use a combination thereof.It should be noted that a silicon oxide system material can exemplify asilicon oxide (SiO_(X)), BPSG, PSG, BSG, AsSG, PbSG, a siliconoxynitride (SiON), SOG (spin-on-glass), and a low-dielectric material(such as polyaryl-ether, cycloperfluorocarbon polymer, benzocyclobutene,an annular fluorine resin, polytetrafluoroethylene, fluoroaryl-ether,fluorinated polyimide, amorphous carbon, or organic SOG).

The solid-state image pickup device can include a surface illuminationtype, or can include a back-illumination type. In addition, thesolid-state image pickup device can constitute a single-plate type colorsolid-state image pickup device. In addition thereto, as may benecessary, the image pickup element may be provided with an on-chipmicrolens or a light blocking layer, and is provided with a drivecircuit and wiring for driving the image pickup element. A shutter forcontrolling the incidence of the light to the image pickup element maybe disposed as may be necessary, or in response to the purpose of thesolid-state image pickup device, the image pickup device may include anoptical cut filter. Moreover, when the image pickup elements in theimage pickup device of the present disclosure is constituted by a singlelayer of the image pickup element of the present disclosure an array ofthe image pickup elements can include a Bayer array, an interline array,a G stripe RB checkered array, a G stripe RB full checkered array, acheckered complementary color array, a stripe array, an oblique stripearray, a primary color difference array, a field color differencesequential array, a frame color difference sequential array, a MOS typearray, an improved MOS type array, a frame interleave array, and a fieldinterleave array. It should be noted that the image pickup element, etc.of the present disclosure can constitute an optical sensor, an imagesensor, and a solar cell in addition to the solid-state image pickupdevice such as a television camera.

Example 1

Example 1 relates an image pickup element according to a first aspectand a second aspect of the present disclosure, a photoelectricconversion element according to the first aspect and the second aspectof the present disclosure, and a solid-state image pickup deviceaccording to a first aspect of the present disclosure.

An image pickup element 11, and a photoelectric conversion element ofExample 1, as depicted in a schematic cross-sectional view of FIG. 1 arean image pickup element 11, and a photoelectric conversion element ineach of which at least a first electrode 21, an organic photoelectricconversion layer 30, and a second electrode 22 are laminated on oneanother in order. That is to say, the image pickup element 11, and thephotoelectric conversion element are each provided with:

(a-1) the first electrode 21 and the second electrode 22 which areprovided separately from each other; and

(a-2) the organic photoelectric conversion layer 30 provided between thefirst electrode 21 and the second electrode 22. Then, the organicphotoelectric conversion layer 30 includes a first organic semiconductormaterial having the structural formula (1) or structural formula (2)described above. In addition, the solid-state image pickup device ofExample 1 is provided with a plurality of image pickup elements 11 ofExample 1. Specifically, the solid-state image pickup device of Example1 is provided with the image pickup elements of Example 1 which arearrayed in a two-dimensional matrix.

The first electrode 21 as the electrode on a light incidence sideincludes a transparent conductive material, specifically, an indium-tinoxide (ITO) having a thickness of 120 nm. In addition, the secondelectrode 22 includes aluminum (Al) having a thickness of 100 nm. Thefirst electrode 21 including the transparent conductive material isformed on the transparent substrate 20, the organic photoelectricconversion layer 30 is formed on the first electrode 21, and the secondelectrode 21 is formed on the organic photoelectric conversion layer 30.In such a way, the second electrode 22 is provided above the secondelectrode 21. The light is made incident to the organic photoelectricconversion layer 30 through the substrate 20 and the first electrode 21.The substrate 20 includes a quartz substrate having a thickness of 0.7mm. Surface roughness of the substrate 20 was R_(a)=0.28 nm, andR_(max)=3.3 nm.

The image pickup element 11 of Example 1 can be manufactured by thefollowing method. That is to say, firstly, an ITO film having athickness of 120 nm was deposited on the substrate 20 including a quartzsubstrate by using a sputtering system, and the first electrode 21including the ITO film was obtained based on a photolithographytechnique and an etching technique. Next, an insulating layer 31 wasformed on the substrate 20 and the first electrode 21. After theinsulating layer 31 was subjected to the patterning based on thephotolithography technique and the etching technique, thereby exposingthe one-mm-square first electrode 21, ultrasonic cleaning was carriedout by using a detergent, acetone, and ethanol. In addition, after thesubstrate was dried, an ultraviolet rays/ozone process was furthercarried out for 10 minutes. Next, the substrate 20 was fixed to asubstrate holder or a vacuum evaporation system, and an evaporationchamber was decompressed to 5.5×10⁻⁵ Pa.

After that, the organic photoelectric conversion layer 30 including amaterial having the structural formula (1) or the structural formula (2)(specifically, having the structural formula (2),2,7-Bis(4-biphenyl)-[1]benzothieno[3,2-b][1]benzothiophene), and theorganic photoelectric conversion layer 30 including fullerene (C60) weredeposited on the first electrode 21. Specifically, the organicphotoelectric conversion layer 30 was deposited at an evaporation rateof 1:1 by using the co-evaporation method to have a thickness of 100 nm.The organic photoelectric conversion layer 30 is constituted by a mixedlayer (bulk-hetero layer) of the p-type organic material, in the presentdisclosure, having the structural formula (2), and fullerene (C60) asthe n-type organic semiconductor.

Thereafter, the second electrode (cathode) 22 including ITO having athickness of 100 nm was deposited by using the sputtering system,thereby obtaining an image pickup element for evaluation of Example 1depicted in a schematically partial cross-sectional view of FIG. 1. Itshould be noted that because of the image pickup element for evaluation,the second electrode included ITO having a thickness of 100 nm.

For an image pickup element of Comparative Example 1, the organicphotoelectric conversion layer 30 included a sub-phthalocyanine systemderivative and fullerene (C60) instead of including the material havingthe structural formula (2) and fullerene (C60). Except for this point,the image pickup element of Comparative Example 1 has the sameconstitution and structure as those of the image pickup element ofExample 1.

The image pickup element of Example 1 and the image pickup element ofComparative Example 1 which were obtained in such a way were irradiatedwith a given quantity of light (=1.64 μW/cm²) having a wavelength of 450nm and a wavelength of 560 nm corresponding to the respective localmaximum optical absorption wavelengths through the substrate 20 and thefirst electrode 21. Then, in a state in which the second electrode 22was grounded, a predetermined voltage (bias voltage) was applied to thefirst electrode 21. A current value obtained at this time exhibits aphoto-generated current value. Values of external quantum efficiencieseach exhibiting the sensitivity of the image pickup element which wasobtained from J-V characteristics concerned are depicted in followingTABLE 1. It should be noted that in TABLE 1, a relative value of theexternal quantum efficiency of the image pickup element of Example 1 isdepicted when a value of the external quantum efficiency of the imagepickup element of Comparative Example 1 is set as “1.” From TABLE 1, itis understood that the external quantum efficiency of the image pickupelement of Example 1 increases approximately 11 times as compared withthe case of the image pickup element of Comparative Example 1.

Moreover, when none of the image pickup element of Example 1 and theimage pickup element of Comparative Example 1 was irradiated with thelight, in a state in which the second electrode 22 is grounded, thepredetermined voltage (bias voltage) was applied to the first electrode21, and thus a carrier (hole) mobility of the p-type semiconductormaterial constituting the organic photoelectric conversion layer 30 wasmeasured. Although the resulting results are depicted in TABLE 1, it isunderstood that the hole mobility in the image pickup element of Example1 extremely increases as compared with the case of the image pickupelement of Comparative Example 1. FIG. 3 depicts a relationship betweenthe hole mobility and the conversion efficiency of the p-typesemiconductor material constituting each of the organic photoelectricconversion layers in the image pickup elements of Example 1 andComparative Example 1.

TABLE 1 External quantum efficiency Hole mobility Example 1 10.8 1.0 ×10⁻² cm²/V · s Comparative Example 1 1.0 4.4 × 10⁻⁷ cm²/V · s

Each of the organic photoelectric conversion layers in the image pickupelements of Example 1 and Comparative Example 1 uses fullerene as then-type semiconductor material. In general, in the image pickup elementconstituted by the organic photoelectric conversion layer including themixed layer (bulk-hetero layer) of the p-type semiconductor material andthe n-type semiconductor material, the p-type semiconductor materialplays the hole transfer, and the n-type semiconductor material plays theelectron transfer, thereby generating the photocurrent. Then, as thecarrier transfer property is higher, the external quantum efficiencyalso becomes high. Here, as depicted in FIG. 3, the hole mobility andthe external quantum efficiency of the image pickup element of Example 1are respectively higher than the hole mobility and the external quantumefficiency of the image pickup element of Comparative Example 1. Thisdepicts that the structural formula (2) has the higher hole transferproperty than that of the sub-phthalocyanine system derivative, and forthis reason, the high external quantum efficiency can be attained. In aword, the organic photoelectric conversion layer is constituted by themixed layer (bulk-hetero layer) of the material of the structuralformula (2), and fullerene, thereby enabling the image pickup elementand the photoelectric conversion element each having the highsensitivity and the high carrier transfer property to be presented.

FIG. 2 depicts a conceptual diagram of a solid-state image pickup deviceof Example 1. A solid-state image pickup device 40 of Example 1 isconstituted by an image pickup region 41, and a vertical drive circuit42, a column signal processing circuit 43, a horizontal drive circuit44, an output circuit 45, a control circuit 46, and the like which areperipheral circuits of the image pickup region 41. In this case, in theimage pickup region 41, the image pickup elements 11 described above arearranged in a two-dimensional array on a semiconductor substrate (forexample, a silicon semiconductor substrate). Incidentally, it goeswithout saying that these circuits can be configured with the well-knowncircuits, and can also be configured by using other circuitconfigurations (for example, the various circuits used in the past CCDimage pickup apparatus or CMOS image pickup apparatus).

The control circuit 46 generates a lock signal and a control signalwhich become a reference of operations of the vertical drive circuit 42,the column signal processing circuit 43, and the horizontal drivecircuit 44 based on a vertical synchronous signal, a horizontalsynchronous signal, and a master clock. In addition, the clock signaland control signal thus generated are inputted to the vertical drivecircuit 42, the column signal processing circuit 43, and the horizontaldrive circuit 44.

The vertical drive circuit 42, for example, is configured by a shiftregister, and selectively scans the respective image pickup elements 11of the image pickup region 41 successively in a vertical direction inunits of a raw. In addition, pixel signals based on currents (signals)which are generated in response to quantities of received light in therespective image pickup elements 11 are sent to the column signalprocessing circuit 43 through vertical signal lines 47.

The column signal processing circuit 43, for example, is arranged everycolumn of the image pickup elements 11 and carries out the signalprocessing for the noise removal and the signal amplification for thesignals outputted from the image pickup elements 11 for one raw by thesignal from a black reference pixel (formed in a circumference of aneffective pixel area although not depicted) every image pickup element.In an output stage of the column signal processing circuit 43, ahorizontal selection switch (not depicted) is connected and providedbetween itself and the horizontal signal line 48.

The horizontal drive circuit 44, for example, is configured by a shiftregister. The horizontal drive circuit 44 successively selects each ofthe column signal processing circuits 43 by successively outputtinghorizontal scanning pulses, and outputs the signals from each of thecolumn signal processing circuits 43 to the horizontal signal line 48.

The output circuit 45 executes signal processing for the signals whichare successively supplied thereto through the horizontal signal line 48from each of the column signal processing circuits 43, and outputs theresulting signals.

Here, since the organic photoelectric conversion layer itself functionsas the color filter as well, the color separation can be carried outeven when no color filter is arranged.

In the image pickup element or the photoelectric conversion element ofExample 1, the material of the structural formula (1) or the structuralformula (2) having the high hole mobility is used in the organicphotoelectric conversion layer, thereby enabling the photoelectricconversion efficiency and the hole mobility to be greatly enhanced. Inaddition, the material of the structural formula (1) or the structuralformula (2) has the high carrier transport ability, the thickness of theorganic photoelectric conversion layer can be adjusted. Thus, theproblems of the high resistance, the low mobility, and the low carrierdensity as the disadvantages which the past organic material has can besolved, and the image pickup element, the photoelectric conversionelement, and the solid-state image pickup device each having the highsensitivity, the high S/N ratio, and the high drive speed can bepresented. Moreover, the thickness of the organic photoelectricconversion layer is adjusted, thereby enabling the spectralcharacteristics of the image pickup element in the solid-state imagepickup device to be adjusted. In addition, fullerene or the fullerenederivative is contained in the material of the structural formula (1) orthe structural formula (2), and/or the p-type organic optical absorptionmaterial or organic transparent material and/or the n-type organicoptical absorption material or organic transparent material is containedin the material of the structural formula (1) or the structural formula(2), thereby resulting in that the thickness and the spectralcharacteristics of the organic photoelectric conversion layer can becontrolled with a high degree of freedom, and the higher performance ofthe solid-state image pickup device can be promoted.

Example 2

Example 2 is a modified change of Example 1. In an image pickup elementor a photoelectric conversion element of Example 2,

the organic photoelectric conversion layer further includes a secondorganic semiconductor material and a third organic semiconductormaterial,

the second organic semiconductor material includes fullerene or afullerene derivative, and

a value μ₃ of a line absorption coefficient in a local maximum opticalabsorption wavelength of a visible light region of the third organicsemiconductor material is larger than a value μ₁ of a line absorptioncoefficient in a local maximum optical absorption wavelength of avisible light region of the first organic semiconductor material, and islarger than a value μ₂ of a line absorption coefficient in a localmaximum optical absorption wavelength of a visible light region of thesecond organic semiconductor material.

Specifically, in Example 2A, organic semiconductor materials depicted infollowing TABLE 3 were used. It should be noted that the third organicsemiconductor material includes a sub-phthalocyanine system derivative.A thickness of the organic photoelectric conversion layer is 250 nm.

On the other hand, in Comparative Example 2A, a quinacridonederivative-A, a quinacridone derivative-B, and the samesub-phthalocyanine system derivative as that used in Example 2A wereused as the organic semiconductor material constituting the organicphotoelectric conversion layer. It should be noted that a thickness ofthe organic photoelectric conversion layer is 180 nm.

The pieces of hole mobility of the first organic semiconductor material,the quinacridone derivative-A, a quinacridone derivative-B, andquinacridone are as depicted in following TABLE 2.

TABLE 2 Hole mobility First organic semiconductor material 1.0 × 10⁻²cm²/V · s Quinacridone derivative-A 8.1 × 10⁻⁸ cm²/V · s Quinacridonederivative-B 1.1 × 10⁻¹⁰ cm²/V · s Quinacridone 3.0 × 10⁻⁶ cm²/V · s

TABLE 3 organic semiconductor materials each constituting organicphotoelectric conversion layer First organic semiconductor Materialhaving structural formula (2) (μ₁ = 0 cm⁻¹, no absorption of green colorregion) Second organic Fullerene (C60) material semiconductor (μ₂ = 0cm⁻¹, no absorption of green color region) Third organic semiconductorSubphthalocyanine system material derivative (μ₃ = 2.6 × 10⁵ cm⁻¹)

In addition, as depicted in FIG. 4, the organic photoelectric conversionlayer has a local maximum optical absorption wavelength in the range of450 nm or more to 650 nm or less.

Measurement results of external quantum efficiencies and dark currentsof Example 2A and Comparative Example 2A are depicted in following TABLE4. It should be noted that TABLE 4 depicts relative values of theexternal quantum efficiency and the dark current of the image pickupelement of Example 2A when values of the external quantum efficiency andthe dark current of the image pickup element of Comparative Example 2Aare set as “1.”

TABLE 4 External quantum efficiency Dark current Example 2A 2.25 0.58Comparative 1.00 1.0 Example 2A

From TABLE 4, it is understood that the image pickup element of Example2A exhibits the high external quantum efficiency, and the low darkcurrent as compared with the case of the image pickup element ofComparative Example 2A.

Then, in the image pickup element or the photoelectric conversionelement of Example 2, the excitons generated by the optical absorptionof the third organic semiconductor material are subjected to the excitonseparation in both the interfaces of the organic semiconductor materialsselected from two of the first organic semiconductor material, thesecond organic semiconductor material, and the third organicsemiconductor material. Alternatively, the excitons generated by theoptical absorption of the third organic semiconductor material aresubjected to the exciton separation in the interface of one kind oforganic semiconductor material selected from the first organicsemiconductor material, the second organic semiconductor material, andthe third organic semiconductor material. Specifically, the excitonsgenerated by the optical absorption of the third organic semiconductormaterial are subjected to the exciton separation in the interfacebetween the first organic semiconductor material and the third organicsemiconductor material. It should be noted that such exciton separationcan be detected based on a method such as a transient absorptionspectrometry and a fluorescent lifetime measurement method.

Now, the sensitivity of the solid-state image pickup device is largelyinfluenced by the efficiency of the exciton charge separation (excitoncharge separation rate) in the bulk-hetero structure. The light madeincident to the organic photoelectric conversion layer excites theelectrons in the organic molecules constituting the organicphotoelectric conversion layer to produce the single excitons. When thesingle excitons diffuse to reach a boundary between the p-typesemiconductor material and the n-type semiconductor material, that is, ap/n junction surface (a conceptual view is depicted in FIG. 5A), thesingle excitons are charge-separated into the holes and the electrons byan internal electric field generated in the p/n junction surface. Forenhancing the sensitivity of the solid-state image pickup device, it isimportant that the exciton charge separation rate is enhanced toincrease the photoelectric conversion efficiency. In general, the singleexcitons of the organic molecules are deactivated for 1 nanosecond to 1microsecond to return back to the ground state. Therefore, forincreasing the photoelectric conversion efficiency, it is preferablethat the exciton charge separation is carried out for a time periodsufficiently shorter than the exciton life, for example, 0.1 nanosecondsor less. From this fact, the exciton charge separation rate in the p/njunction surface is preferably 1×10¹⁰ s⁻¹ or more.

The exciton charge separation rate was calculated by the theoreticalsimulation. Firstly, for example, diphenylbenzothienobenzothiophene(2,7-Diphenyl[1]benzothieno[3,2-b][1]benzothiophene, DPh-BTBT) as aderivative of benzothienobenzothiophene, and, for example, F6SubPc-OC6F5[refer to the structural formula (18)] as a derivative ofsub-phthalocyanine are used. Here, DPh-BTBT relatively functions as thep-type semiconductor material, and F6SubPc-OC6F5 relatively functions asthe p-type semiconductor material. Then, a p/n junction surfacestructure of 6×6×6 nm³ depicted in FIG. 5B was manufactured by using amolecular dynamics method. DPh-BTBT has a molecular structure in whichthe phenyl group is removed away one by one from the side chain of theboth sides of the first organic semiconductor material depicted by thestructural formula (2) and has the same main skeleton as that of thefirst organic semiconductor material. In general, since the excitonseparation of the organic semiconductor material is generated betweenthe main skeletons, the evaluation for other organic semiconductormaterial having the same main skeleton as that of a certain organicsemiconductor material can be carried out based on the result ofsimulation for the certain organic semiconductor material (for example,refer to T. Liu et al., J. Phy. Chem. C 115, 2406 (2011)). Therefore,the result of the simulation for DPh-BTBT is effective in evaluating thefirst organic semiconductor material depicted by the structural formula(2). Subsequently, a dimer of DPh-BTBT and F6SubPc-OC6F5 in which theexciton charge separation rate was desired to be obtained was selectedfrom the structure depicted in FIG. 5B to take out the molecules eachhaving the center of gravity within a radius of 2.5 nm from the centerof gravity of DPh-BTBT. FIG. 5C depicts the structure thus taken out.The molecule which is ball-and-stick displayed is the dimer in which theexciton charge separation rate is desired to be obtained, and themolecule which is line-displayed is the peripheral molecule. The excitonstate calculation was carried out with respect to the structure of FIG.5C. In the exciton state calculation, there was used a QM/MM method inwhich the dimer in which the exciton charge separation rate was desiredto be obtained was calculated with the quantum mechanics, and theperiphery molecule was calculated with the molecular mechanics. Theexciton charge separation rate which was desired to be obtained in thedimer was obtained based on a Marcus theory (refer to R. A. Marcus, Rev.Mod. Phys. 65, 599 (1993)). In the Marcus theory, the exciton chargeseparation rate (charge-transfer rate) ω_(ab) between an initial state(state a) and a final state (state b) is expressed by followingExpression (A).

ω_(ab)=(H _(ab) ² /h){(π/(λ·k _(B) T)}^(1/2)·exp[(−(ΔG+λ)²/(4Δk _(B)T)]   (A)

Here,

H_(ab): transfer integration between two states (charge transferintegration)

h: reduced Plank constant (Dirac constant)

λ: relocation energy

k_(B): Boltzmann's constant

T: absolute temperature

ΔG: Gibbs' free energy difference between two states.

ΔG and λ between the respective excited states are calculated asfollows. Firstly, a single excited state is obtained from a firstexcited singlet state S₁ to tenth excited singlet state S₁₀, and thestructural optimization is carried out with respect to the respectiveexcited states to obtain an energy stable structure. Subsequently, aviburational calculation is carried out for the energy stable structuresof the respective excited states to calculate the free energy. As aresult, ΔG and λ between the respective excited states are calculated.H_(ab) is calculated by using a generalized-Mulliken-Hush method (referto R. J. Cave et al., J. Chem. Phys. 106, 9213 (1997)). The excitoncharge separation rate in the p/n junction surface between DPh-BTBT andF6SubPc-OC6F5 was obtained with respect to the excitons generated withinF6SubPc-OC6F5. TABLE 5 lists the exciton charge separation ratescalculated by using Expression (A).

TABLE 5 exciton charge separation rate [unit: s⁻¹] F6SubPc- ChargeExciton charge OC6F5 separation separation exciton state rate state S₁S₃ 2.6 × 10¹² S₁ S₄ 2.7 × 10¹⁰ S₁ S₅ 2.3 × 10¹⁰ S₂ S₃ 2.7 × 10¹² S₂ S₄5.4 × 10¹¹ S₂ S₅ 7.9 × 10¹¹

From the above results, it was understood that the high exciton chargeseparation rate of 1×10¹⁰ s⁻¹ or more was obtained in the p/n junctionsurface between DPh-BTBT and F6-SubPc-OC6F5. That is to say, it isunderstood that the excellent photoelectric conversion efficiency wasobtained in the image pickup element (photoelectric conversion element)provided with the organic photoelectric conversion layer in which thep/n junction surface having the high exciton charge separation rate of1×10¹⁰ s⁻¹ or more.

Alternatively, the organic photoelectric conversion layer furtherincludes a fourth organic semiconductor material. The fourth organicsemiconductor material may be provided with a mother skeleton similar tothat of the first organic semiconductor material, or may have the samemother skeleton as that of either the second organic semiconductormaterial or the third organic semiconductor material, and may beprovided with a substituent different therefrom. Specifically, thefourth organic semiconductor material has the same mother skeleton(specifically, a sub-phthalocyanine system derivative) as that of thethird organic semiconductor material, and is provided with the differentsubstitutent. More specifically, the fourth organic semiconductormaterial includes the sub-phthalocyanine system derivative F6SubPc-F[refer to the structural formula (17)]. In such a way, the organicphotoelectric conversion layer includes the fourth organic semiconductormaterial, thereby enabling the excellent spectral characteristics to beobtained. Alternatively, the fourth organic semiconductor material hasthe mother skeleton (specifically, benzothienobenzothiophene) similar tothat of the first organic semiconductor material. More specifically, thefourth organic semiconductor material includes DPh-BTBT. That is to say,the organic photoelectric conversion layer includes the fourth organicsemiconductor material, thereby enabling the excellent hole transportproperty to be obtained.

The enhancement of the carrier mobility is essential to the promotion ofthe enhancement of the operation frequency of the image pickup element,the reduction of the residual image in the image pickup element, theenhancement element of the photoelectric conversion efficiency of theimage pickup element (photoelectric conversion element). In the imagepickup element (photoelectric conversion element) of Example 2a, asdescribed above, the organic photoelectric conversion layer furthercontains the second organic semiconductor material and the third organicsemiconductor material. Then, an area (overlap area) of a portion inwhich the energy distribution state density of HOMO or LUMO of thesecond organic semiconductor material, and the energy distribution statedensity of HOMO or LUMO of the third organic semiconductor materialoverlap each other is 0.15 meV or more. Moreover, the energydistribution σ of the third organic semiconductor material or the energydistribution σ of the second organic semiconductor material is 70 meV orless. Here, the second organic semiconductor material includes eitherfullerene or the fullerene derivative, and the third organicsemiconductor material includes the sub-phthalocyanine systemderivative.

Specifically, the stable structure is built by carrying out thesimulation based on the molecular dynamics method (MD method) (Step 1).Then, the adjacent molecule pair is drawn from this structure and atransfer integrated value (J_(ij)) is calculated by carrying out thefirst principle calculation. In addition, an HOMO energy and an LUMOenergy (site energy E_(i)) in each of which the effect of the adjacentmolecules is taken into consideration are calculated (Step 2). Next, thecharge transfer rate (ω_(ij)) is calculated based on Expression (A)described above by using a Marcus theory from the resulting transferintegrated value (J_(ij) and side energy E_(i)). Then, a dynamicbehavior of the carrier is simulated from a dynamic Moute Carlo method(kMC method) by using the resulting transfer rate (ω_(ij)) (Step 3).Then, the mobility μ is calculated by using the following Einsteinrelation from the resulting mean square displacement (MSD) of thecarrier. Here, the energy distribution of the molecules is obtained fromthe site energy calculated in Step 2. Then, when the energydistributions of the two molecules are each obtained, an overlap areacan be obtained from the overlap of the distributions.

μ=(q/k _(B) T)·D

Here,

q: electric charge

k_(B): Boltzmann's constant

T: absolute temperature

D: diffusion coefficient

The overlap area of the energy distributions of LUMO which was obtainedbased on the various second organic semiconductor material and thirdorganic semiconductor material, and the energy distribution σ of thethird organic semiconductor material are depicted in following TABLE 6.In addition, the states of overlap of the energy distributions of LUMOwhich were obtained based on the second organic semiconductor materialand the third organic semiconductor material are depicted in FIG. 8(Example 2B and Example 2C), FIG. 9 (Example 2D and Example 2E), FIG. 10(Example 2F and Example 2G), FIG. 11 (Comparative Example 2B andComparative Example 2C), FIG. 12 (Comparative Example 2D and ComparativeExample 2E), FIG. 13 (Comparative Example 2F and Comparative Example2G), and FIG. 14 (Comparative Example 2H and Comparative Example 21). Inthese drawings, however, a unit of an abscissa axis is meV and anordinate axis represents the energy of LUMO. It should be noted that inFIG. 8 to FIG. 14, “A” is data on C60, “B” is data on F6SubPc-OC5F6, theabscissa axis is the energy (unit: meV), and the ordinate axis is theprobability density (unit: arbitrary). In addition, Example 2B, Example2C, Example 2D, Example 2E, Example 2F, Comparative Example 2B,Comparative Example 2C, Comparative Example 2D, Comparative Example 2E,Comparative Example 2F, and Comparative Example 2G are examples in whichthe materials are used in which an average value shift amount of energydistribution σ of C60 or the energy distributions of F6SubPc-OC6F5 isvirtually changed on the simulation. Moreover, a relationship betweenthe overlap area of the energy distributions of LUMO, and the relativevalue of the carrier mobility is depicted in the graph of FIG. 6. Arelationship between the value of the energy distribution σ of LUMO ofthe second organic semiconductor material, and the carrier mobility isdepicted in the graph of FIG. 7. From FIG. 6, it is understood that anincrease in overlap area results in that the relative value of thecarrier mobility increases. In addition, it is also understood that asthe value of the energy distribution σ of LUMO of the second organicsemiconductor material is smaller, the carrier mobility becomes high.Here, when the carrier mobility becomes 10⁻⁴ cm²/V·s or more, forexample, the residual image characteristics are improved in thesolid-state image pickup device, and thus the high-speed continuousphotographing becomes possible which cannot be perceived by the eyes ofthe human being. Therefore, from the results described above, it isunderstood that when the area (overlap area) of the portion in which theenergy distribution state density of LUMO of the second organicsemiconductor material, and the energy distribution state density ofLUMO of the third organic semiconductor material overlap each other is0.15 meV or more, and when the energy distribution σ of the thirdorganic semiconductor material or the energy distribution σ of thesecond organic semiconductor material is 70 meV or less, the highcarrier mobility can be attained.

TABLE 6 Average Energy Energy value shift Overlap distribution (σ)distribution (σ) amount area meV meV meV meV Ex. 2B C60 29.5F6-SubPc-OC6F5 131.8 — 0.230 Ex. 2C C60 29.5 F6-SubPc-OC6F5 131.8 +20.00.198 (Δμ = +20) Ex. 2D C60 29.5 F6-SubPc-OC6F5 131.8 +40.0 0.168 (Δμ =+40) Ex. 2E C60 70.0 F6-SubPc-OC6F5 131.8 — 0.425 (σ = 70) Ex. 2F C6050.0 F6-SubPc-OC6F5 131.8 — 0.342 (σ = 50) Ex. 2G C60 40.0F6-SubPc-OC6F5 131.8 — 0.291 (σ = 40) Comp. Ex. C60 29.5 F6-SubPc-OC6F5131.8 +200.0 0.0238 2B (Δμ = +200) Comp. Ex. C60 29.5 F6-SubPc-OC6F5131.8 +160.0 0.0427 2C (Δμ = +160) Comp. Ex. C60 29.5 F6-SubPc-OC6F5131.8 +120.0 0.0720 2D (Δμ = +120) Comp. Ex. C60 29.5 F6-SubPc-OC6F5131.8 +80.0 0.114 2E (Δμ = +80) Comp. Ex. C60 190.0 F6-SubPc-OC6F5 131.8— 0.620 2F (σ = 190) Comp. Ex. C60 150.0 F6-SubPc-OC6F5 131.8 — 0.595 2G(σ = 150) Comp. Ex. C60 110.0 F6-SubPc-OC6F5 131.8 — 0.534 2H (σ = 110)Comp. Ex. F6-SubPc-OC6F5 131.8 — 2I

Example 3

Although Example 3 is a modified change of the image pickup element ofExample 1 and Example 2, Example 3 relates to the laminated image pickupelement of the present disclosure, and the solid-state image pickupdevice according to a second aspect of the present disclosure. That isto say, in the laminated image pickup element (image pickup element oflongitudinal spectroscopic system) of Example 3, at least the two imagepickup elements described in Example 1 and Example 2 are laminated oneach other. In addition, the solid-state image pickup device of Example3 is provided with a plurality of such laminated image pickup elements.Specifically, the laminated image pickup element of Example 3, asdepicted in a conceptual view of FIG. 15A, has a structure in which thethree image pickup elements (three sub-pixels): the image pickup elementfor a blue color; the image pickup element for a green color; and theimage pickup element for a red color which are described in Example 1and Example 2 are laminated on one another in the vertical direction.That is to say, it is possible to obtain the laminated image pickupelement having the structure in which the sub-pixels are laminated onone another to be made one pixel. The image pickup element for a bluecolor is located in the uppermost layer, the image pickup element for agreen color is located in the intermediate layer, and the image pickupelement for a red color is located in the lowermost layer. However, theorder of the lamination is by no means limited to that order.

Alternatively, as depicted in a conceptual view of FIG. 15B, the imagepickup elements (in a depicted example, the image pickup element for ablue color and the image pickup element for a green color) eachdescribed in Example 1 and Example 2 are provided on the siliconsemiconductor substrate and one or a plurality of photoelectricconversion areas (the image pickup elements, and in the depictedExample, the image pickup element having the sensitivity to the redcolor) is provided in the inside of the silicon semiconductor substratelocated below such image pickup elements. As a result, it is possible toobtain the laminated image pickup element having the structure in whichthe image pickup elements are laminated on one another, that is, thestructure in which the sub-pixels are laminated on one another to bemade one pixel.

Alternatively, the image pickup elements (for example, the image pickupelement for a blue color or the image pickup element for a green color)described in Example 1 and Example 2 is provided on the siliconsemiconductor substrate, and one or a plurality of photoelectricconversion regions (image pickup elements) is provided in the inside ofthe silicon semiconductor substrate located below such image pickupelements. As a result, it is possible to obtain the laminated imagepickup element having the structure in which the image pickup elementsare laminated on one another, that is, the structure in which thesub-pixels are laminated on one another to be made one pixel.Alternatively, the image pickup elements (for example, three kinds ofimage pickup elements: the image pickup element for a blue color; theimage pickup element for a green color; and the image pickup element fora red color) described in Example 1 and Example 2 are provided on thesilicon semiconductor substrate, and the photoelectric conversion region(image pickup element) having the sensitivity to the infrared ray isprovided in the inside of the silicon semiconductor substrate locatedbelow each of these image pickup elements. As a result, it is alsopossible to obtain the laminated image pickup element having thestructure in which the image pickup elements are laminated on oneanother, that is, for example, having one pixel including three kinds ofsub-pixels. That is to say, each of these laminated image pickupelements is configured to have at least one first image pickup element(one first image pickup element, or a plurality of image pickup elementsor laminated first image pickup elements) provided on(in) thesemiconductor substrate (specifically, the silicon semiconductorsubstrate or the compound semiconductor substrate), and a second imagepickup element provided above the first image pickup element(s). Thesecond image pickup element is composed of the image pickup elementaccording to the first aspect and the second aspect of the presentdisclosure.

Although the photoelectric conversion region (image pickup element)formed on(in) the silicon semiconductor substrate is preferably of abackside illumination type, instead thereof, a surface illumination typecan also be adopted. Instead of providing the photoelectric conversionregion in the inside of the silicon semiconductor substrate, thephotoelectric conversion region can also be formed on the semiconductorsubstrate by using an epitaxial growth method, or can also be formedon(in) a silicon layer in the so-called SOI structure.

In the laminated image pickup element of Example 3, for the purpose ofprevented the light reception of the image pickup element located belowfrom being disturbed, in the image pickup element located above, thefirst electrode, for example, includes the transparent conductivematerial such as ITO, and the second electrode, for example, alsoincludes the transparent conductive material such as ITO. This can alsoapply to the photoelectric conversion element.

In the solid-state image pickup device of Example 3 provided with thelaminated image pickup elements, the spectrum of the blue color, thegreen color, and the red color is not carried out by using the colorfilters, but the image pickup elements having the sensitivities to thelight having a plurality of kinds of wavelengths are laminated on oneanother in the direction of incidence of the light within the samepixels. Therefore, it is possible to enhance the improvement in thesensitivity, and the improvement in the pixel density per unit volume.In addition, since the organic material has the high absorptioncoefficient, the thickness of the organic photoelectric conversion layercan be more thinned than that of the past Si system photoelectricconversion layer. As a result, it is possible to relax the light leakagefrom the adjacent pixel(s), and the limitation of an incidence angle ofthe light. Moreover, in the past Si system image pickup element, thefalse color occurs because the color signals are produced by executingthe interpolation processing among the pixels corresponding to therespective three colors. However, in the solid-state image pickup deviceof Example 3 provided with the laminated image pickup elements, theoccurrence of the false color is suppressed.

Although the present disclosure has been described so far based onpreferred Examples, the present disclosure is by no means limited thesepreferred Examples. The structures, the configurations, themanufacturing conditions, the manufacturing methods, and the usedmaterials of the image pickup element, the photoelectric conversionelements, the laminated image pickup element, and the solid-state imagepickup device which have been described in Examples areexemplifications, and thus can be suitably changed. When thephotoelectric conversion element of the present disclosure is made tofunction as the solar cell, it is only necessary to irradiate theorganic photoelectric conversion layer with the light in a state inwhich no voltage is applied across the first electrode and the secondelectrode.

The molecular structure is no object as long as the first organicsemiconductor material has the high hole transport ability (for example,the hole mobility is 1×10⁻⁴ cm²/V·s or more, preferably 1×10⁻³ cm²/V·sor more, and more preferably 1×10⁻² cm²/V·s or more). For example, thefirst organic semiconductor material can be constituted by the materialhaving the benzothiophene structure as the partial skeleton of thestructural formula (1) or the structural formula (2), or the structuralformula (101) to the structural formula (116). Here, benzothiophene isone of the partial structures of acenedichalcogenophene, and thus hasthe high hole transfer ability. Alternatively, the first organicsemiconductor material can be constituted by the acenedichalcogenophenesystem organic material.

It should be noted that the present disclosure can also adopt thefollowing constitutions.

[A01] <<Image Pickup Element: First Aspect>>

An image pickup element constituted by laminating at least a firstelectrode, an organic photoelectric conversion layer, and a secondelectrode in order, the organic photoelectric conversion layer includinga first organic semiconductor material having the following structuralformula (1):

where R₁ and R₂ are each groups independently selected from hydrogen, anaromatic hydrocarbon group, a heterocyclic group, a halogenated aromaticgroup, or a fused heterocyclic group, and have an optional substituent;

the aromatic hydrocarbon group is an aromatic hydrocarbon group selectedfrom the group consisting of a phenyl group, a naphthyl group, ananthryl group, a phenanthryl group, a pyrenyl group, and a benzopyrenylgroup;

the heterocyclic group is a heterocyclic group selected from the groupconsisting of a pyridyl group, a pyradyl group, a pyrimidyl group, aquinolyl group, an isoquinolyl group, a pyrrolyl group, an indolenylgroup, an imidazolyl group, a thienyl group, a furyl group, a pyranylgroup, and a pyridonyl group;

the halogenated aromatic group is a halogenated aromatic group selectedfrom the group consisting of a phenyl group, a naphthyl group, ananthryl group, a phenanthryl group, a pyrenyl group, and a benzopyrenylgroup; and

the fused heterocyclic group is a fused heterocyclic group selected fromthe group consisting of a benzoquinolyl group, an anthraquinolyl group,and a benzothienyl group.

[A02] <<Image Pickup Element: Second Aspect>>

An image pickup element constituted by laminating at least a firstelectrode, an organic photoelectric conversion layer, and a secondelectrode in order,

the organic photoelectric conversion layer including a first organicsemiconductor material having the following structural formula (2):

[A03]

The image pickup element described in [A01] or [A02], in which theorganic photoelectric conversion layer further includes a second organicsemiconductor material, the second organic semiconductor materialincludes either fullerene or a fullerene derivative.

[A04]

The image pickup element described in [A01] or [A02], in which theorganic photoelectric conversion layer further includes a second organicsemiconductor material and a third organic semiconductor material;

the second organic semiconductor material includes either fullerene or afullerene derivative; and

a value μ₃ of a line absorption coefficient in a local maximum opticalabsorption wavelength of a visible light region of the third organicsemiconductor material is larger than a value μ₁ of a line absorptioncoefficient in a local maximum optical absorption wavelength of avisible light region of the first organic semiconductor material, and islarger than a value μ₂ of a line absorption coefficient in a localmaximum optical absorption wavelength of a visible light region of thesecond organic semiconductor material.

[A05]

The image pickup element described in [A04], in which an excitongenerated by optical absorption of the third organic semiconductormaterial is subjected to exciton separation in both interfaces of theorganic semiconductor materials selected from two of the first organicsemiconductor material, the second organic semiconductor material, andthe third organic semiconductor material, or an exciton generated byoptical absorption of the third organic semiconductor material issubjected to exciton separation in an interface of one kind of organicsemiconductor material selected from the first organic semiconductormaterial, the second organic semiconductor material, and the thirdorganic semiconductor material.

[A06]

The image pickup element described in [A05], in which an exciton chargeseparation rate at which the exciton is subjected to the excitonseparation is 1×10¹⁰ s⁻¹ or more.

[A07]

The image pickup element described in any one of [A04] to [A06], inwhich the organic photoelectric conversion layer has a local maximumoptical absorption wavelength in the range of 450 nm or more to 650 nmor less.

[A08]

The image pickup element described in any one of [A04] to [A07], inwhich the third organic semiconductor material includes asub-phthalocyanine system derivative.

[A09]

The image pickup element described in any one of [A04] to [A08], inwhich the organic photoelectric conversion layer further includes afourth organic semiconductor material; and

the fourth organic semiconductor material includes a mother skeletonsimilar to that of the first organic semiconductor material, or has thesame mother skeleton as that of either the second organic semiconductormaterial or the third organic semiconductor material, and includes adifferent substituent.

[A10]

The image pickup element described in [A01] or [A02], in which theorganic photoelectric conversion layer further includes a second organicsemiconductor material and a third organic semiconductor material; and

an area in a portion in which an energy distribution state density ofhighest occupied molecular orbital or lowest unoccupied molecularorbital of the second organic semiconductor material, and the an energydistribution state density of HOMO or LUMO of the third organicsemiconductor material overlap each other is 0.15 meV or more.

[A11]

The image pickup element described in [A10], in which an energydistribution σ of the third organic semiconductor material or an energydistribution σ of the second organic semiconductor material is 70 meV orless.

[A12]

The image pickup element described in [A10] or [A11], in which thesecond organic semiconductor material includes either fullerene or afullerene derivative.

[A13]

The image pickup element described in any one of [A10] to [A12], inwhich the third organic semiconductor material includes asub-phthalocyanine system derivative.

[A14]

The image pickup element described in any one of [A01] to [A13], inwhich hole mobility of the first organic semiconductor material is1×10⁻⁵ cm²/V·s or more.

[A15]

The image pickup element described in any one of [A01] to [A14], inwhich the first electrode and the second electrode include a transparentconductive material.

[A16]

The image pickup element described in any one of [A01] to [A14], inwhich one of the first electrode and the second electrode includes atransparent conductive material, and the other includes a metallicmaterial.

[A17]

The image pickup element described in any one of [A01] to [A16], inwhich a wavelength of an optical absorption peak in an opticalabsorption spectrum of the organic photoelectric conversion layer fallswithin a visible light region.

[A18]

The image pickup element described in any one of [A01] to [A17], inwhich an optical absorption spectrum of the organic photoelectricconversion layer has one local maximum value in the visible lightregion.

[A19]

The image pickup element described in any one of [A01] to [A18], inwhich an absorption coefficient of the organic photoelectric conversionlayer is 1×10⁵ or more.

[A20]

The image pickup element described in any one of [A01] to [A19], inwhich a sublimation temperature under an atmosphere of a materialconstituting the organic photoelectric conversion layer is 250° C. ormore.

[B01] <<Laminated Image Pickup Element>>

A laminated image pickup element constituted by laminating at least twoimage pickup elements described in any one of [A01] to [A20].

[C01] <<Solid-state Image Pickup Device: First Aspect>>

A solid-state image pickup device comprising a plurality of image pickupelements described in any one of [A01] to [A20].

[C02] <<Solid-state Image Pickup Device: Second Aspect>>

A solid-state image pickup device comprising a plurality of laminatedimage pickup elements described in [B01].

[D01] <<Photoelectric Conversion Element: First Aspect>>

A photoelectric conversion element constituted by laminating at least afirst electrode, an organic photoelectric conversion layer, and a secondelectrode in order, the organic photoelectric conversion layer includinga first organic semiconductor material having the following structuralformula (1):

where R₁ and R₂ are each groups independently selected from hydrogen, anaromatic hydrocarbon group, a heterocyclic group, a halogenated aromaticgroup, or a fused heterocyclic group, and have an optional substituent;

the aromatic hydrocarbon group is an aromatic hydrocarbon group selectedfrom the group consisting of a phenyl group, a naphthyl group, ananthryl group, a phenanthryl group, a pyrenyl group, and a benzopyrenylgroup;

the heterocyclic group is a heterocyclic group selected from the groupconsisting of a pyridyl group, a pyradyl group, a pyrimidyl group, aquinolyl group, an isoquinolyl group, a pyrrolyl group, an indolenylgroup, an imidazolyl group; a thienyl group, a furyl group, a pyranylgroup, and a pyridonyl group;

the halogenated aromatic group is a halogenated aromatic group selectedfrom the group consisting of a phenyl group, a naphthyl group, ananthryl group, a phenanthryl group, a pyrenyl group, and a benzopyrenylgroup; and

the fused heterocyclic group is a fused heterocyclic group selected fromthe group consisting of a benzoquinolyl group, an anthraquinolyl group,and a benzothienyl group.

[D02] <<Photoelectric Conversion Element: Second Aspect>>

A photoelectric conversion element constituted by laminating at least afirst electrode, an organic photoelectric conversion layer, and a secondelectrode in order,

the organic photoelectric conversion layer including a first organicsemiconductor material having the following structural formula (2):

[D03]

The photoelectric conversion element described in [D01] or [D02], inwhich the organic photoelectric conversion layer further includes asecond organic semiconductor material; and

the second organic semiconductor material includes either fullerene or afullerene derivative.

[D04]

The photoelectric conversion element described in [D01] or [D02], inwhich the organic photoelectric conversion layer further includes asecond organic semiconductor material and a third organic semiconductormaterial;

the second organic semiconductor material is constituted by eitherfullerene or a fullerene derivative; and

a value μ₃ of a line absorption coefficient in a local maximum opticalabsorption wavelength of a visible light region of the third organicsemiconductor material is larger than a value μ₁ of a line absorptioncoefficient in a local maximum optical absorption wavelength of avisible light region of the first organic semiconductor material, and islarger than a value μ₂ of a line absorption coefficient in a localmaximum optical absorption wavelength of a visible light region of thesecond organic semiconductor material.

[D05]

The photoelectric conversion element described in [D04], in which anexciton generated by optical absorption of the third organicsemiconductor material is subjected to exciton separation in bothinterfaces of the organic semiconductor materials selected from two ofthe first organic semiconductor material, the second organicsemiconductor material, and the third organic semiconductor material, oran exciton generated by optical absorption of the third organicsemiconductor material is subjected to exciton separation in aninterface of one kind of organic semiconductor material selected fromthe first organic semiconductor material, the second organicsemiconductor material, and the third organic semiconductor material.

[D06]

The photoelectric conversion element described in [D05], in which anexciton charge separation rate at which the exciton is subjected to theexciton separation is 1×10¹⁰ s⁻¹ or more.

[D07]

The photoelectric conversion element described in any one of [D04] to[D06], in which the organic photoelectric conversion layer has a localmaximum optical absorption wavelength in the range of 450 nm or more and650 nm or less.

[D08]

The photoelectric conversion element described in any one of [D04] to[D07], in which the third organic semiconductor material includes asub-phthalocyanine system derivative.

[D09]

The photoelectric conversion element described in any one of [D04] to[D08], in which the organic photoelectric conversion layer furtherincludes a fourth organic semiconductor material; and

the fourth organic semiconductor material includes a mother skeletonsimilar to that of the first organic semiconductor material, or has thesame mother skeleton as that of either the second organic semiconductormaterial or the third organic semiconductor material, and includes adifferent substituent.

[D10]

The photoelectric conversion element described in [D01] or [D02], inwhich the organic photoelectric conversion layer further includes asecond organic semiconductor material and a third organic semiconductormaterial; and

an area in a portion in which an energy distribution state density ofhighest occupied molecular orbital or lowest unoccupied molecularorbital of the second organic semiconductor material, and the an energydistribution state density of highest occupied molecular orbital orlowest unoccupied molecular orbital of the third organic semiconductormaterial overlap each other is 0.15 meV or more.

[D11]

The photoelectric conversion element described in [D10], in which anenergy distribution σ of the third organic semiconductor material or anenergy distribution σ of the second organic semiconductor material is 70meV or less.

[D12]

The photoelectric conversion element described in [D10] or [D11], inwhich the second organic semiconductor material includes eitherfullerene or a fullerene derivative.

[D13]

The photoelectric conversion element described in any one of [D10] to[D12], in which the third organic semiconductor material includes asub-phthalocyanine system derivative.

[D14]

The photoelectric conversion element described in any one of [D01] to[D13], in which hole mobility of the first organic semiconductormaterial is 1×10⁻⁵ cm²/V·s or more.

[D15]

The photoelectric conversion element described in any one of [D01] to[D14], in which the first electrode and the second electrode include atransparent conductive material.

[D16]

The photoelectric conversion element described in any one of [D01] to[D14], in which one of the first electrode and the second electrodeincludes a transparent conductive material, and the other includes ametallic material.

[D17]

The photoelectric conversion element described in any one of [D01] to[D16], in which a wavelength of an optical absorption peak in an opticalabsorption spectrum of the organic photoelectric conversion layer fallswithin a visible light region.

[D18]

The photoelectric conversion element described in any one of [D01] to[D17], in which an optical absorption spectrum of the organicphotoelectric conversion layer has one local maximum value in thevisible light region.

[D19]

The photoelectric conversion element described in any one of [D01] to[D18], in which an absorption coefficient of the organic photoelectricconversion layer is 1×10⁵ or more.

[D20]

The photoelectric conversion element described in any one of [D01] to[D19], in which a sublimation temperature under an atmosphere of amaterial constituting the organic photoelectric conversion layer is 250°C. or more.

REFERENCE SIGNS LIST

-   -   11 . . . Image pickup element (photoelectric conversion        element), 20 . . . Substrate, 21 . . . First electrode, 22 . . .        Second electrode, 30 . . . Organic photoelectric conversion        layer, 31 . . . Convex portion, 40 . . . Solid-state image        pickup device, 41 . . . Image pickup area, 42 . . . Vertical        drive circuit, 43 . . . Column signal processing circuit, 44 . .        . Horizontal drive circuit, 45 . . . Output circuit, 46 . . .        Control circuit, 47 . . . Vertical signal line, 48 . . .        Horizontal signal line

1-21. (canceled)
 22. An image pickup element comprising a firstelectrode, an organic photoelectric conversion layer, and a secondelectrode in order, the organic photoelectric conversion layer includinga first organic semiconductor material and a second organicsemiconductor material, wherein the first organic semiconductor materialhas the following structural formula (1):

where R₁ and R₂ are each groups independently selected from hydrogen, anaromatic hydrocarbon group, a heterocyclic group, a halogenated aromaticgroup, and a fused heterocyclic group, each group having an optionalsubstituent, wherein the second organic semiconductor material includeseither fullerene or a fullerene derivative, and wherein the organicphotoelectric conversion layer is a bulk hetero layer and the firstorganic semiconductor material is a p-type material and the secondorganic semiconductor material is an n-type material.
 23. The imagepickup element of claim 22, wherein the first organic semiconductormaterial is represented by the following structural formula (2):


24. The image pickup element according to claim 22, wherein the aromatichydrocarbon group is selected from the group consisting of a phenylgroup, a naphthyl group, an anthryl group, a phenanthryl group, apyrenyl group, and a benzopyrenyl group, wherein the heterocyclic groupis selected from the group consisting of a pyridyl group, a pyradylgroup, a pyrimidyl group, a quinolyl group, an isoquinolyl group, apyrrolyl group, an indolenyl group, an imidazolyl group, a thienylgroup, a furyl group, a pyranyl group, and a pyridonyl group, whereinthe halogenated aromatic group is selected from the group consisting ofa halogenated phenyl group, a halogenated naphthyl group, an halogenatedanthryl group, a halogenated phenanthryl group, a halogenated pyrenylgroup, and a halogenated benzopyrenyl group; and wherein the fusedheterocyclic group is selected from the group consisting of abenzoquinolyl group, an anthraquinolyl group, and a benzothienyl group.25. The image pickup element according to claim 22, wherein thefullerene derivative comprises a halogen atom, a straight chain,branched or cyclic alkyl group or phenyl group, a group having astraight chain or condensed aromatic compound, a group having a halide,a partial fluoroalkyl group, a perfluoroalkyl group, a cyrilalkyl group,a cyrilalkoxy group, an allycyril group, an allylsulfanyl group, analkylsulfide group, an allylsulphonyl group, an alkylsulphonyl group, anallylsulfany group, an alkylsulfide group, an amino group, an alkylaminogroup, an allylamino group, a hydroxy group, an alkoxy group, anacylamino group, an acyloxy group, a carbonyl group, a carboxy group, acarboxythoamido group, a carboalkoxy group, an acyl group, a sulfonylgroup, a cyano group, a nitro group, a group having a chalcogenide, aphosphine group, a phosphonate group, or a combination thereof.
 26. Theimage pickup element according to claim 22 wherein the organicphotoelectric conversion layer further comprises a p-type organicoptical absorption material or a p-type organic transparent material.27. The image pickup element according to claim 26, wherein the p-typeorganic optical absorption material or the p-type organic transparentmaterial comprises a fused ring system compound, a heteromonocyclicsystem compound, a fused heterocyclic system compound, a polymethinesystem compound, a π conjugated low-molecular-weight system compound, acarbonium compound, a styryl system compound, a stilbene systemcompound, a metal complex system compound, a π conjugated polymer systemcompound, a π conjugated system compound, a dye-containing polymericsystem compound, and a polymer complex system compound.
 28. The imagepickup element according to claim 22, wherein the organic photoelectricconversion layer further comprises n-type organic optical absorptionmaterial or an n-type organic transparent material.
 29. The image pickupelement according to claim 28, wherein the n-type organic opticalabsorption material or the n-type organic transparent material comprisesa fused ring system compound, a heteromonocyclic system compound, afused heterocyclic system compound, a polymethine system compound, a πconjugated low-molecular-weight system compound, a carbonium compound, astyryl system compound, a stilbene system compound, a metal complexsystem compound, a π conjugated polymer system compound, a π conjugatedsystem compound, a dye-containing polymeric system compound, and apolymer complex system compound.
 30. The image pickup element accordingto claim 22, wherein the organic photoelectric conversion layer has athickness from 1×10⁻⁸ m to 7×10⁻⁷ m.
 31. The image pickup elementaccording to claim 22, wherein the organic photoelectric conversionlayer has a local maximum optical absorption wavelength in the range of450 nm to 650 nm.
 32. The image pickup element according to claim 22,wherein the hole mobility of the first organic semiconductor material is1×10⁻⁵ cm²/V·s or more.
 33. The image pickup element according to claim22, wherein the first electrode and the second electrode include atransparent conductive material.
 34. The image pickup element accordingto claim 22, wherein one of the first electrode and the second electrodeincludes a transparent conductive material, and the other of the firstelectrode or the second electrode includes a metallic material.
 35. Alaminated image pickup element constituted by laminating at least twoimage pickup elements according to claim
 22. 36. A solid-state imagepickup device comprising a plurality of image pickup elements accordingto claim 22 arrayed in a two-dimensional matrix on a semiconductorsubstrate.
 37. A solid-state image pickup device comprising a pluralityof laminated image pickup elements according to claim 35 arrayed in atwo-dimensional matrix on a semiconductor substrate.
 38. A photoelectricconversion element constituted by laminating at least a first electrode,an organic photoelectric conversion layer, and a second electrode inorder, the organic photoelectric conversion layer including a firstorganic semiconductor material and a second organic semiconductormaterial, wherein the first organic semiconductor material has thefollowing structural formula (1):

where R₁ and R₂ are each groups independently selected from hydrogen, anaromatic hydrocarbon group, a heterocyclic group, a halogenated aromaticgroup, and a fused heterocyclic group, each group having an optionalsubstituent, wherein the second organic semiconductor material includeseither fullerene or a fullerene derivative, and wherein the organicphotoelectric conversion layer is a bulk hetero layer and the firstorganic semiconductor material is a p-type material and the secondorganic semiconductor material is an n-type material.
 39. Thephotoelectric conversion element of claim 38, wherein the first organicsemiconductor material is represented by the following structuralformula (2):


40. A method for manufacturing an image pickup element comprising thesteps of: (i) depositing a first electrode on a transparent substrate;(ii) forming an insulating layer on the substrate and the firstelectrode; (iii) patterning the insulating layer to expose a portion ofthe first electrode; (iv) depositing an organic photoelectric conversionlayer on the exposed portion of the first electrode, wherein the organicphotoelectric conversion layer includes a first organic semiconductormaterial and a second organic semiconductor material, wherein the firstorganic semiconductor material has the following structural formula (1):

where R₁ and R₂ are each groups independently selected from hydrogen, anaromatic hydrocarbon group, a heterocyclic group, a halogenated aromaticgroup, and a fused heterocyclic group, each group having an optionalsubstituent, wherein the second organic semiconductor material includeseither fullerene or a fullerene derivative, wherein the first organicsemiconductor material is a p-type material and the second organicsemiconductor material is an n-type material and wherein the firstorganic semiconductor material and a second organic semiconductormaterial are deposited to form a bulk hetero film; and (v) depositing asecond electrode on the photoelectric conversion layer.
 41. The methodof claim 40, further comprising laminating at least two image pickupelements.